Читать книгу First Bite: How We Learn to Eat - Bee Wilson - Страница 8

Every man carries within him a world, which is composed of all that he has seen and loved, and to which he constantly returns, even when he is travelling through, and seems to be living in, some different world.

FRANÇOIS-RENÉ DE CHATEAUBRIAND, Travels in Italy, 1828

‘He won’t eat anything but cornflakes,’ complained the mother of a boy I used to know. Breakfast, lunch or dinner – always a bowl of cornflakes and milk. Even at other people’s houses, this boy made no concessions. To his mother, his extreme diet was a source of worry and exasperation. To the rest of us, he was a fascinating case study. Secretly, I was slightly in awe of him; my sister and I would never have dared be so fussy. To look at, you wouldn’t know there was anything different about this kid: scruffy blond hair, big grin, neither unduly skinny nor chubby. He was not socially withdrawn or difficult in any other way. Where did it come from, this bizarre cornflake fixation? It just seemed to be part of his personality, something no one could do anything about.

Whether you are a child or a parent, the question of ‘likes and dislikes’ is one of the great mysteries. Human tastes are astonishingly diverse, and can be mulishly stubborn. Even within the same family, likes vary dramatically from person to person. Some prefer the components of a meal to be served separate and unsullied, with nothing touching; others can only fully enjoy them when the flavours mingle in a pot. There is no such thing as a food that will please everyone. My oldest child – a contrarian – doesn’t like chocolate; my youngest – a conformist – adores it. It’s hard to say how much of this has to do with chocolate actually tasting different to each of them and how much it has to do with the social pay-off you get from being the person who either likes or loathes something so central to the surrounding culture. The one who loves chocolate gets the reward of enjoying something that almost everyone agrees is a treat. And he gets a lot of treats. The one who doesn’t like chocolate gets fewer sweets, but what he does get is the thrill of surprising people with his oddball tastes. He fills the chocolate-shaped void with liquorice.

Yet my chocolate-hating boy will happily consume pieces of chocolate if they are buried in a cookie or melted in a mug of hot cocoa. One of the many puzzles about likes and dislikes is how they change depending on the context. As the psychologist Paul Rozin says: ‘to say one likes lobster does not mean that one likes it for breakfast or smothered in whipped cream.’¹ Different meals, different times of day and different locations can all make the same food or drink seem either desirable or not. Call it the retsina effect: that resinated white wine that is so refreshing when sipped on a Greek island tastes of paint-stripper back home in the rain. It’s also worth remembering that when we say we like this or that, though we use the same words, we are often not talking about the same thing. You may think you hate ‘mango’ because you have only ever tasted the fibrous, sour-yellow kind. When I say I adore it, I am thinking of a ripe Alphonso mango from India, brimming with orange juice and so fragrant you could bottle it and use it for perfume.

The foods we eat the most are not always the ones we like the most. In 1996 the psychologist Kent Berridge changed the way that many neuroscientists thought about eating when he introduced a distinction between ‘wanting’ (the motivation to eat something) and ‘liking’ (the pleasure that the food actually gives).² Berridge found that ‘wanting’ or craving was neurally as well as psychologically distinct from ‘liking’. Whereas the zone of the brain that controls our motivation to eat stretches across the entire nucleus accumbens, the sections of the brain that give us pleasure when we eat occupy smaller ‘hotspots’ within this same area. For Berridge, this discovery offers a fruitful way for thinking about some of the ‘disorders of desire’ that bedevil humans. For example, binge eating may – like other addictive behaviours – be associated with ‘excessive wanting without commensurate “liking”’.³ You may feel a potent drive to purchase an extra-large portion of cheesy Nachos even though the pleasure they deliver when you actually consume them is much less potent than you expected. Indeed, binge eaters often report that the foods they crave do not even taste good when they are eating them: the desire is greater than the enjoyment.

However, several neuroscientists have pointed out in response to Berridge that liking and wanting remain ‘highly entangled’.⁴ Berridge himself admits that there is strong evidence that if you reduce the amount a food is liked, the consequence is that it is also wanted less.⁵ Even if our craved foods do not make us as happy as we hope they will, the reason that we crave them in the first place is because we once loved them.⁶ Like drug addicts, we are chasing a remembered high. Our ‘likes’ thus remain a central motivating force in shaping how and what we eat. To find out more about why we like the foods we do remains a vital question for anyone who is interested in feeding themselves or their family better. If asked to say where tastes come from, I suspect that most of us would say they were determined by individual temperament, which is another way of saying ‘genes’. Being a chocolate lover – or hater – becomes so much part of our self-image that we can’t imagine ourselves any other way. We show that we are adventurous by seeking out the hottest chillis; we prove we are easy-going by telling our host we ‘eat anything’. We confirm that we are naturally conservative by eating patriotic hunks of red meat. Taste is identity. Aged eight, my daughter used to draw pictures of herself and write ‘prawns-peas-mushrooms’ at the top, surrounding herself with the tastes she loved best.

Because our tastes are such an intimate part of ourselves, it is easy to make the leap to thinking that they must be mostly genetic: something you just have to accept as your lot in life. Parents often tell children that their particular passions place them on this or that side of the family – you got your fussiness from your grandfather! – as if you were destined from birth to eat a certain way. Sometimes it is uncanny how a suspicion of celery or a deep hunger for blackberries replicates from parent to child. When we notice these familial patterns, it confirms us in our view that food preferences must be inherited through our genes.

When I’ve described the argument of this book to people I meet, sometimes they get a little angry. ‘I disagree that we learn how to eat,’ they say. ‘You’d never get me to like sultanas/squid/salami [delete as appropriate].’ Anyway, they say, ‘What about genes?’

It’s fine by me if you don’t like sultanas. And I’m certainly not denying that there is a genetic component in our relationship with food. We are not born as blank slates. Some people have a heightened genetic sensitivity to certain flavours (notably bitterness) while others are blind to them.⁷ There are also genetic variations in individual appetite, the speed at which we eat and the extent to which people actually enjoy eating.⁸ We vary in how we chew, how we swallow and how we digest. Some people are born with conditions that make it much harder to eat, such as a delay to the oral-motor system. I had no idea quite how fraught the basic matter of getting food from plate to mouth could be until my third child was born with cleft palate and he and I both struggled at mealtimes. He is now five and new dishes occasionally still provoke tears (usually his). Our relationship with food and weight is additionally affected by epigenetics: our experience in the womb. The ‘thrifty phenotype’ hypothesis of biochemist C. Nicholas Hales and epidemiologist David Barker suggests that being undernourished in utero leaves people with a lifelong propensity for weight gain, an unfair fate to be handed so early.⁹

The question remains to what extent we are capable of overriding this genetic and epigenetic inheritance and learning new tastes. This riddle can seem impossible to unravel, given that children do not learn to eat under laboratory conditions. As we take our first bites, our parents are supplying us simultaneously with both nature (genes) and nurture (environment conceived in its broadest sense, including everything from cuisine to family dynamics to religion to cutlery and table manners to the ethics of meat to views on whether it’s OK to eat food off the floor if it was only there for five seconds). The two are so intertwined, it’s hard to tell where one starts and the other stops.

In one remarkable experiment, however, a group of children did learn to eat under lab conditions. In the 1920s and 1930s, Dr Clara Davis, a paediatrician from Chicago, spent six years trying to study what children’s appetites would look like if allowed to blossom in total freedom without any preconceived ideas of what tasted good.¹⁰ Davis’s results have often been taken as a clear indication that likes and dislikes are fundamentally inbuilt and natural though, as we’ll see, Davis herself drew a rather different conclusion.

In 1926, at Mt Sinai Hospital in Cleveland, Dr Clara Marie Davis started the most influential experiment ever conducted into the question of human likes and dislikes. As a doctor, Davis saw many children with eating problems – mostly refusal to eat – whose appetites did not match their nutritional needs. She wondered what children’s appetites would look like, freed from the usual pressures of parents and doctors pushing them to eat nutritious foods such as hot cereal and milk, regardless of whether they liked them. Conventional medical wisdom at that time was that children’s particular likes should not be indulged, lest they became ‘faddy’. Dr Davis was not so sure that eating what you liked was automatically a bad thing.

She borrowed a number of infants – some of them orphans from institutions and some the children of teenage mothers and widows – and placed them on a special ‘self-selection diet’ under her medical care. The children – aged from six to eleven months, who had never yet tasted solid food – were offered a selection of whole, natural foods and given free rein, day after day, to eat only what they wished. The full list of foods was:

1 Water

2 Sweet milk

3 Sour (lactic) milk

4 Sea salt

5 Apples

6 Bananas

7 Orange juice

8 Fresh pineapple

9 Peaches

10 Tomatoes

11 Beets

12 Carrots

13 Peas

14 Turnips

15 Cauliflower

16 Cabbage

17 Spinach

18 Potatoes

19 Lettuce

20 Oatmeal

21 Wheat

22 Corn meal

23 Barley

24 Ry-Krisp

25 Beef

26 Lamb

27 Bone marrow

28 Bone jelly

29 Chicken

30 Sweetbreads (offal from the pancreas)

31 Brains

32 Liver

33 Kidneys

34 Fish (haddock)11

At each meal, the infants were offered a selection of around ten foods from this list, all of them mashed, ground up or finely minced. Some, such as bone marrow, beef, peas and carrots, were offered both in cooked and raw form. The selection was laid out in bowls, while nurses sat by, waiting to see what the children would choose. As Davis described it:

The nurse’s orders were to sit quietly by, spoon in hand, and make no motion. When, and only when, the infant reached for or pointed to a dish might she take up a spoonful and, if he opened his mouth for it, put it in. She might not comment on what he took or did not take, point to or in any way attract his attention to any food, or refuse him any for which he reached. He might eat with his fingers or in any way he could without comment or correction of his manners.¹²

Davis continued this experiment over a period of six years, starting with three babies and building up to fifteen. The results, which have been hotly discussed by doctors ever since, were dramatic. Without any preconceived notions about what foods were suitable for them, the babies showed enthusiasm for everything from bone marrow to turnips. They didn’t realize they weren’t supposed to like beets or offal. All of them tried all of the thirty-four foods, except for two who never attempted lettuce and one who shunned spinach.

Within a few days, Davis noticed, ‘they began to reach eagerly for some and to neglect others, so that definite tastes grew under our eyes.’¹³ It soon became obvious to her that for the fifteen children, there were ‘fifteen different patterns of taste’. The children made some very odd selections which looked like a ‘dietician’s nightmare’ said Davis. They went on curious ‘food jags’. One day, they might gorge on liver or eat a meal of nothing but bananas, eggs and milk. A boy called Donald showed a rare passion for oranges, cramming in nearly two pounds of them one day.¹⁴ In the process of trial and error of finding out what tasted nice, some of the children ‘chewed hopefully’ on plates and spoons, while others grabbed handfuls of pure salt. On trying something new, Davis observed that their faces showed first surprise, then indifference, pleasure or dislike.

However bizarre and unbalanced the children’s likes and dislikes look to our eyes, they served them well. In a 1928 article writing up her findings, Dr Davis included a ‘before’ and ‘after’ photo of one of the children, Abraham G. At eight months, on arriving in her care, he looks a little pale. At twenty months, after a year on the diet, he is cherubic and plump.

When they arrived at the hospital the infants were generally in poor health. Four were seriously underweight; five had rickets. Yet within a few months, all the children were pink-cheeked and optimally nourished. One of the rickets sufferers was offered cod liver oil, which he took the occasional glug of; but the other four managed to get enough vitamin D and calcium to cure their rickets through diet alone. When they suffered colds, they appeared to self-medicate, eating vast amounts of carrots, beets and raw beef. Even though they were given no guidance on what their bodies needed, their ratio of calories averaged at protein 17 per cent, fat 35 per cent and carbohydrate 48 per cent, very much in line with contemporary nutritional science.

Dr Davis created an unprecedented body of information on childish appetites (though it was never fully analysed and, after her death in 1959, all the boxes of raw data were discarded). When Davis took up a new job, the original set-up in Cleveland was moved to Chicago, where she established what amounted to ‘an eating-experiment orphanage’. In all, she logged around 36,000 meals as well as recording changes in height and weight, blood and urine, bowel movements and bone density.¹⁵ It is unlikely any scientist will ever get such detailed data again, given the dubious ethics of keeping children locked up in an experimental nursery for so long. The babies stayed on the diet for a minimum of six months and a maximum of four and a half years, during which time they were always at the hospital.

No friends visited and those who were not orphans had little or no contact with their parents. While in the hospital nursery, their lives were subordinated to the needs of the experiment. Such an arrangement would never be allowed now, though Davis evidently cared for the children very much, in her way. She adopted two of them, as a single mother: Abraham G (the plump cherub) and Donald, the passionate orange eater. Many years later, after Donald was dead, his widow recalled that he and Abraham had always been ‘easy to cook for’ and ‘happy to try all kinds of foods’; they remained omnivores all their lives.¹⁶

It was such an extraordinary, audacious, borderline-crazy project that Davis attempted: to get to the heart of where children’s food passions come from. It’s just a shame that her experiment proved so easy to misread. Time and again, Davis’s orphanage has been held up as evidence that appetite is mostly genetic and, as a consequence, that the foods children like or dislike are a sure guide to what their bodies need.¹⁷ Davis’s food orphanage has been taken as proof that in their natural state, likes and dislikes are genetic and highly individual, like fingerprints: our tastes are a matter of nature, not nurture. What this interpretation fails to take account of is that the biggest thing Dr Davis did was to radically restructure the food environment of the children.

There was a ‘trick’ to the way the experiment was set up, as Clara Davis was the first to point out. The real secret was in her choice of the thirty-four foods, which were all unprocessed whole foods. With such foods preselected for them, it didn’t matter which ones the children were drawn to on any given day, because, assuming they took food from several of the bowls at each meal, they could not help but eat a diet of an excellent standard of nutrition. Davis said that her choice of food was designed to mimic the conditions of ‘primitive peoples’, though the heaping bowlfuls were surely more plentiful than any hunter-gatherer regime. The experiment proved that when your only food choices are good ones, preferences become unimportant. The ‘fifteen patterns of taste’ resulted in a single healthy whole-food diet, because of the set-up. None of the children was totally omnivorous, but nor were their likes and dislikes a problem, as they so often are in normal family life. There was no option to like unhealthy food and dislike healthy food.

Davis herself concluded that her experiment showed that the selection of food for young children should be left ‘in the hands of their elders where everyone has always known it belongs’. Instead of the ‘wisdom of the body’ Davis spoke of the ‘glaring fallibility of appetite’. It was obvious to her that there was no ‘instinct’ pointing blindly to the ‘good’ and the ‘bad’ in food. The two most popular foods overall in her study were also the sweetest: milk and fruit. Had she offered the children a free choice of ‘sugar and white flour’, those staples of a 1930s diet, it is unlikely they would have ended up in such fine fettle. Self-selection, she concluded, would have little or no value if the children were selecting from ‘inferior foods’.

The real test, Davis recognized, would be to offer newly weaned infants a choice between natural foods and processed food. This was to have been her next experiment, but the Depression dashed this prospect, as her funding ran out at the crucial moment. Davis never got the chance to test the effects on appetite of the ‘pastries, preserves, gravies, white bread, sugar and canned food’ that had in her lifetime become so popular. Davis’s experiment left a powerful legacy that took no account of the trick at the heart of it. Doctors, particularly in America, interpreted her experiment to mean that children’s appetites are inbuilt and benign, without paying attention to the way in which Davis had changed the food environment in which the babies ate. Her work was seized on as proof that our individual appetites are messages encoded with exactly the nutrients that our particular body needs. If we need protein, we will crave chicken. If we have rickets, we will naturally gorge on vitamin D until we are cured. All we have to do to eat well is listen to our cravings. Mother Nature knows best. Davis herself gave licence to such a view, commenting that the children’s successful ‘juggling and balancing’ of more than thirty essential nutrients suggested ‘the existence of some innate, automatic mechanism … of which appetite is a part’.¹⁸

Influenced by Davis, the dominant view on appetite among paediatricians became ‘the wisdom of the body’, which went along with the vogue for ‘child-centred’ learning. In 2005 Benjamin Scheindlin MD, a paediatrician, noted that Davis’s work contributed to a widespread change in attitudes in paediatric medicine from the 1930s onwards.¹⁹ Where a previous generation lamented the pickiness of children’s changeable tastes, now doctors positively welcomed childish vagaries of appetite. Dr Spock, author of the bestselling Baby and Child Care, first published in 1946, devoted ten pages to the Davis experiment. A mother, in Spock’s opinion ‘can trust an unspoiled child’s appetite to choose a wholesome diet if she serves him a reasonable variety and balance’.²⁰ It didn’t matter if a child developed a temporary dislike of a vegetable, because their cravings would naturally give them everything they needed in the way of nutrition.

Many experts in child-rearing still think like this, operating on the assumption that children are born with special appetites for exactly the nutrients they most need and that it will all balance out, if only they are given free rein to eat what they like. A book on solving children’s eating problems that went through several reprints in the 1980s and 1990s argued that the implications of Davis’s work were that children should be given total control over food selection: let them eat cornflakes!²¹ As recently as 2007, a popular website about feeding children discussed Davis and concluded that there was ‘a strong biological plausibility … that children will instinctively choose a balanced diet’.²²

The ‘wisdom of the body’ is an alluring thought (like maternal instinct and other biological myths). Eating would be such a simple business, if only we had little memos inside our bodies telling us what we needed to eat at each precise moment (your vitamin C levels are dropping – quick, eat a kiwifruit!). If only we liked just the stuff that was good for us and disliked anything superfluous or bad. We can certainly learn to get better at reading our body’s cues for food, but this tends to come with age and experience, as you notice little things like how pasta for lunch makes you sleepy or that a handful of nuts and a cup of Greek yoghurt keep you full for longer than white toast and jam. But children’s omnivorous bodies – after the milk stage, when breastfed infants do self-regulate – are not so wise.

Many children habitually seek out precisely the foods that are least suitable for them. They crave sugar and shun green vegetables. They neglect to drink enough water. Nutritious meals are rejected, while junk is revered. Can we really believe that a preschooler demanding a packet of the latest kids’ sugary breakfast cereal, having seen it on TV, is responding to their body’s need for certain vitamins and carbohydrate?

The scientific evidence – both from humans and rats – shows that the theory of the ‘wisdom of the body’ is flawed at best. For the theory to be true, omnivores would need to have specific appetites for the essential nutrients the body needed at any given time. This is a very unlikely proposition, given that the list of nutrients needed by omnivores comes in so many guises, depending on the environment we happen to live in. An innate appetite for the vitamin C in blackcurrants would be no use if you lived somewhere that blackcurrants do not grow. In lab conditions, rats – our fellow omnivores – have shown a very erratic ability to self-select the diet that would do them the most nutritional good. In one study, a group of rats were given a choice between a bad-tasting but protein-rich diet and a good-tasting but low-protein diet. Over the course of a week, fourteen out of eighteen rats failed to develop a preference for the food that would have done them the most good and they lost weight.²³ Other trials have attempted to find out whether rats could ‘self-select’ to correct certain vitamin deficiencies; and concluded that many of them could not. With thiamine-deprived rats, the process of learning to like a thiamine-rich diet took a week or more and the rats who did not adapt quickly enough to the correct food died.²⁴ As for human subjects, there is, notes one specialist in the field, no data to suggest innate appetites for specific foods. It does seem possible for humans to learn over time specific appetites that will correct certain imbalances – particularly a craving for salt when lacking in sodium – but that is a different matter.²⁵

Ninety years after Davis’s experiment, the view that likes are predominantly innate – or genetic – looks shaky. When trying to get to the bottom of where tastes come from, scientists have often turned to twins. If identical twins share more food likes than non-identical twins, the chances are that there is a genetic cause. Twin studies suggest that many aspects of eating are indeed somewhat heritable. Body weight – measured as BMI – appears to be highly heritable in both boys and girls.²⁶ So is dietary ‘restraint’, or the mysterious urge to resist eating the thing you want to eat.²⁷ But studies that look at likes and dislikes are much less conclusive. Several twin studies have suggested that identical twins are more likely to enjoy the same protein foods than non-identical twins, but when it came to snacks, dairy and starchy foods, their likes were only marginally more similar than those of the non-identical twins.²⁸ Overall, the evidence for tastes being heritable is very modest, accounting for only around 20 per cent – at most – of the variation in foods eaten.²⁹

Genes are only ever part of the explanation for what we choose to eat. As one senior doctor working with obese children put it to me, you could be cursed with all the genes that make a person susceptible to heart disease and obesity and still grow up healthy, by establishing balanced food habits. ‘All of it is reversible,’ he said. Parents and children resemble each other no more in the foods they like than couples do, suggesting that nurture – who you eat with – is more powerful than nature in determining our food habits.³⁰ Whatever our innate dispositions, our experience with food can override them. Maybe the reason you share your parent’s hatred of celery is because you have seen them recoil from it at the dinner table.³¹ Researchers found that when they gave three groups of preschool children different varieties of tofu – one group had plain tofu, one ate it with sugar and one with salt – they quickly came to prefer whichever one they had been exposed to, regardless of their genes.³² It turns out that, so far from being born with genetically predetermined tastes, our responses to food are remarkably open to influence, and remain so throughout our lives.

If you want to know what foods a person does and does not like, the single most important question you can ask is not ‘What are your genes?’ but rather ‘Where are you from?’³³ Had he lived in a part of the world where cornflakes are hard to come by, the cornflake boy would have had to find another way to annoy his parents. To a large extent, children eat – and therefore like – what’s in front of them, particularly in conditions of scarcity. ‘If you want your children to be less fussy about what they eat,’ a friend who had fallen on hard times during the recession advised me, ‘I can recommend poverty.’ It’s not really an option to be picky about the staple food of rice if you live in rural China.

Genes do make a difference – to the foods we like, the way we taste them and even how much we enjoy eating – but they turn out to be much less significant than the environment we learn to eat in. Contrary to our deepest beliefs about ourselves and our children, our likes and dislikes – the important ones, anyway, such as whether we eat enough vegetables or how much variety and balance we have in our diets – are much more about nurture than nature. Apart from changing the infants’ food environment, there was another bigger trick to Davis’s experiment, which she did not mention, perhaps because it is so obvious. She radically changed their social experience when eating, removing all extraneous social influence. In place of the hubbub of the family dinner table, the babies had only expressionless nurses who ‘might not comment’ in any way on their choices. The thought of being served in this silent, impassive way is creepy, particularly for the oldest children, who must have been as old as five by the time they left the orphanage. They ate without anyone caring what they ate; without any siblings fighting them for the last slice of pineapple; without any surrounding ideas about cuisine.

Davis was mistaken if she thought this was the way to discover the true nature of children’s appetites. Though the nutritional outcomes were excellent, it was a not-quite-human way to eat, and one which no child in a real situation will ever replicate. We cannot arrive at the truth about appetite by removing all social influences. Appetite is a profoundly social impulse. To a large extent, our likes and dislikes are a response to the environment we eat in. From our first toothless tastes, we are picking up cues about which foods are desirable, and which are disgusting, which sadly are so often the very ones the grown-ups most want us to eat.

The public discussion of eating habits is focused on temptation and the idea of resisting desirable foods. But if we look at eating through the eyes of a child, we see that disgust may be even more powerful than desire in forming our tastes. Our urge to avoid eating something that makes us feel sick is often at the root of disordered eating, as we swerve away from whole categories of foods that we imagine would make us feel queasy. The most common reason for disgust is nausea: anything eaten just before a bout of stomach bug may be hated for life. Psychologist Paul Rozin, the world’s leading expert on disgust, has argued that a central feature of disgust is ‘contagion: when a disgusting food touches otherwise acceptable foods, it renders them permanently inedible’.³⁴ And yet most of the foods that we happen to find disgusting are not toxins but perfectly edible and wholesome foods. Brussels sprouts, for example.

If there is one food associated with personal dislikes in the Anglo-Saxon world, it is the Brussels sprout. Many people assume they have no choice in this matter – they just can’t stand them. Are they right? In an article singing the praises of Brussels sprouts, the great chef Yotam Ottolenghi noted that there was a ‘genetic explanation for why people either love or loathe’ these little green brassicas.³⁵ Ottolenghi argued that being a sprout hater was likely to be a consequence of having a certain gene – TAS2R38 – which ‘makes a protein that reacts with a chemical called PTC to create the sensation of bitterness’. Could this really be true? Is there a molecular basis to our hatred – or otherwise – of green vegetables?³⁶

Some people definitely taste certain flavours more acutely than others. To take one of the stranger examples, up to 30 per cent of the population cannot physically pick up on androstenone, one of the key aromas that make truffles such a luxury. If you served them a sumptuous plate of pappardelle with truffle shavings, they would have no idea why it was meant to cause such joy. A different minority have a heightened sensitivity to coriander leaf, making it taste soapy and gross, rather than herbal and fresh. And, as Ottolenghi says, we vary hugely in our response to bitter tastes. All babies find bitterness somewhat horrible, which is probably a survival mechanism, given that in the wild, toxic substances tend to be bitter. The bitter response of a newborn includes arched lips, a protruding tongue, an expression of anger and spitting: all pretty vivid signs that babies do not consider bitterness to be yummy. Over time, however, it is possible to learn to love bitter substances: witness the fact that the world’s two most popular beverages are coffee and beer.

Some learn to love bitterness; some tolerate it because they enjoy the buzz they get from a bottle of IPA or a cup of strong cafetière coffee; and some hardly taste it at all. Linda Bartoshuk of Yale University was the first to use the term ‘supertaster’ in the mid-1990s to refer to individuals with a heightened response to certain tastes, predominantly bitter ones (the phenomenon was first observed in the 1930s). Bartoshuk and colleagues found that there were significant genetic differences in the way we perceive bitterness. PROP (6-n-propylthiouracil) and PTC (phenylthioucarbamide) are chemical substances that either taste incredibly bitter or slightly bitter or of nothing at all, depending on whether you have the gene to taste them.³⁷ Around half of us are medium tasters, a quarter are non-tasters and another quarter are supertasters. Women are more likely to be supertasters than men. Bartoshuk has shown that PROP supertasters have more taste buds on their tongue than non-tasters. There’s a very simple way to self-diagnose whether you are a supertaster or not. Swab your tongue with a little blue food dye and place a hole punch reinforcer ring on your tongue. Count how many pink bumps you can see inside the ring – these are the fungiform papillae, each containing 3–5 taste buds. If fewer than 15, you are a non-taster. If 15–35 you are a medium taster. If more than 35, you are a supertaster.

Psychologists got excited about the concept of PROP tasting, because it seemed to hold out – at last – the genetic key to likes and dislikes. Could bitter sensitivity be the secret of why some people eat unhealthy diets with few or no vegetables? Is it because they lack a gene for sprouts? The world of flavour must be a very different place to PROP supertasters and non-tasters and it would appear obvious that this would translate into food habits. When seventy-one women and thirty-nine men were asked to taste asparagus, kale and Brussels sprouts, the PROP supertasters did indeed find the vegetables to be more bitter and less sweet.³⁸

The surprising thing, however, is that, from a mass of research into PROP tasting, very little does point to genes determining food choices, either in children or adults.³⁹ Over time, your PROP status is not a particularly strong predictor of what your likes and dislikes will be. If anything, PROP non-tasters – the ones who can’t taste bitterness in the sprouts at all – are slightly more at risk of an unhealthy diet and weight than the PROP supertasters.

There’s clear evidence that PROP supertasters are more sensitive to certain flavours: the burn of chilli, the warmth of cinnamon, the acrid glow of coffee, the rasp of alcohol, the aftertaste of sweeteners and grapefruit – all these are perceived more strongly, often unpleasantly so. What is not so predictable is how this affects preferences. Given that supertasters perceive alcoholic drinks as more bitter, you’d expect them to drink less of them – indeed being a non-taster has been identified in some studies (though not others) as a risk factor for alcoholism: if whisky tasted like water, how easily it might go down. But a study of young adults found that being a PROP taster did not predict how much beer was drunk. After decades of enjoying countless glasses of wine from all the great terroirs in the world, the leading wine writer Jancis Robinson found out that she was a supertaster, something that in theory should make wine taste odiously acrid to her. That’s not how it turned out. As she put it: ‘If I enjoy wine less than the rest of you, you are very lucky wine drinkers indeed.’⁴⁰

When it comes to childhood, the key question is whether being a PROP taster sets you up for a lifetime of disliking the leafy green vegetables every nutritionist wants us to eat more of. Greens – especially those in the cabbage family – contain bitter-tasting glucosinolate compounds. One study suggested that PROP-tasting children were more likely to dislike raw broccoli, but not cooked broccoli. Another study found that when offered black olives, cucumber and raw broccoli, PROP non-taster children ate a larger quantity than tasters did.⁴¹ But when studies have looked at actual preferences rather than what children are prepared to eat in front of researchers, the signs are that PROP tasting in no way dooms you to dislike bitter vegetables. When 525 Irish children (aged seven to thirteen) were asked to record their intake and liking of cabbage, cauliflower, Brussels sprouts and broccoli over a three-day period, there were few significant differences between tasters and non-tasters.⁴² The supertasters did show a marginally lower liking for Brussels sprouts and non-tasters liked cauliflower the most. But when their consumption of bitter vegetables overall was totalled up and averaged out, there were no differences in intake for PROP tasters and non-tasters. In this study, being a PROP taster mattered less than the simple fact of whether these Irish children were boys or girls: girls tended to like bitter vegetables more, or at least to be polite enough to pretend that they did.

A 2013 survey of college students pointed to a similar conclusion. The supertasters and the non-tasters showed no marked difference in likes and dislikes for: Brussels sprouts, broccoli, cabbage, spinach, crushed red pepper, jalapeño peppers, red wine, beer, salad dressing, mayonnaise.⁴³ The only substances that emerged as having significant negative connotations for PROP tasters were dark chocolate, coffee and chilli: the dark pungent end of the bitter flavour spectrum. The team of researchers concluded that environment mattered more than genes in determining preference. In America, they noted, many people ‘know they are not going to like spinach, tofu, liver or “healthy food” and learn that fast food burgers, soda pop and sweet breakfast cereals are delicious … before they ever take a bite’.⁴⁴

Some of the most telling research to date on PROP tasters looked at how genes interacted with the food environment children were growing up in and confirmed that household income and access to good food are more critical in forming tastes than being a supertaster. Over five years from 2005 to 2010, researchers studied 120 New York children aged four to six. Their PROP status was measured and they were deemed to be living in either a ‘healthy food environment’ or an ‘unhealthy food environment’, as judged by the slightly crude method of dividing the number of healthy food sellers by the number of unhealthy food sellers within a half-mile radius of where they lived.⁴⁵ In a healthy food environment, likes and dislikes followed the pattern that Ottolenghi – and common sense – would suggest. In this experiment, unlike the Irish one mentioned above, the PROP non-taster children who couldn’t detect bitterness did indeed show a higher acceptance of vegetables – with fewer dislikes – than taster children in the same healthy environment. The interesting – and troubling – result was what happened to the children in the unhealthy food environment. Here, the likes and dislikes of tasters and non-tasters were not very different. The big difference was in the BMI of the children. In the unhealthy environment, the non-taster children had a higher BMI than any of the other groups studied. Their average BMI was over 1.6, which counts as obese.

What matters most for determining whether your tastes will be healthy ones is not whether you have a sprout-hating gene but the way that your genetic predispositions interact with your food environment. Once environment is taken into account, being a non-taster poses bigger health risks in our current state of plenty and junk than being a supertaster. Several studies have now found that non-tasters – adults as well as children – are the ones who tend to have higher BMIs. The theory is that non-tasters – since they do not experience certain flavours with the same intensity – are more responsive to the influences around them, for good or ill. They learn their likes more easily than supertasters. In a healthy food environment, they will easily acquire healthy tastes. When offered vegetables, they are less likely than supertasters to dismiss them as too bitter. But if they learn to love the wrong foods, the non-tasters can find themselves – like those New York children – obese by the age of six.

So, no, you can’t blame your dislike of sprouts simply on having a faulty gene. If everyone’s first nibble of sprouts was of Ottolenghi’s own sprouts with caramelized garlic and lemon peel, charred in a hot pan until sweetly blackened at the edges, maybe they would be the most popular of all the vegetables. Perhaps your parents were sprout haters and – without meaning to – turned you against them. Or perhaps they forced them on you too vehemently. I know someone – a PROP supertaster, as it happens – who says she can never enjoy Brussels sprouts – though she has no quarrel with broccoli – because of memories of Christmas Day, when she was compelled by her parents to cut each hated sprout into quarters, and swallow them unchewed, like bitter pills. Maybe you never actually tasted sprouts because you ‘knew’ you wouldn’t like them, because in our society the child who loves sprouts is considered a little odd. When the food writer Michele Humes arrived in the US from Hong Kong, it took her a while to get her head around the concept that ‘children weren’t supposed to like vegetables’.⁴⁶

Likes and dislikes cannot be reduced to molecules and genes. This is bad news for the more sensationalist health pages, which thrive on headlines like ‘Revealed: the Obesity Gene’. For the rest of us, it is – potentially – excellent information. It means that our food habits are not final and fixed but adaptable and open, if only we will give ourselves half a chance. We did not come into the world disliking bitter greens; we were taught to dislike them by our environment. Taste may be identity but it is not destiny. The hope – and admittedly it’s a slim one at present for the children whose dislikes are vegetables and whose likes are all junk – is that while we are stuck with our genes, the environment is something that can change.

The main way we learn to like foods is simply by trying them. The term ‘mere exposure’ was coined by Robert Zajonc in 1968.⁴⁷ Zajonc’s thesis was that affection is triggered by familiarity; and that disliking, conversely, is fear of the novel. Some of Zajonc’s early experiments involved showing subjects complex shapes for very short periods of time. When the subjects were later asked to choose their favourite shapes from a line-up, there was a marked preference for the shapes that they had already encountered. Zajonc has suggested that there are similar forces at work when we favour Brie over Camembert.⁴⁸ These cravings are a function of prior experience. One or other cheese may trigger a recognition in us that we cannot necessarily put into words. Zajonc later observed this phenomenon of ‘mere exposure’ at work across cultures and species.

It’s a truism that we know what we like and we like what we know. If you ask young children which foods they most detest, they tend to be the ones they have never actually tasted, often vegetables. To an adult, this sounds crazy: you can’t know if you hate something until you have tasted it. ‘Go on – you might like it!’ I find myself urging, ineffectually, at the dinner table. But to a child, there is nothing paradoxical in saying, ‘I don’t like it – I never tried it!’⁴⁹ The foods that ranked highly on the ‘never tried’ list of a group of seventy American eight-year-olds included avocado (49/70 had never tried it), beetroot (48), prunes (43), collard greens (49), rye bread (43), lima beans (39), radish (38) and fried liver (55).⁵⁰

The children’s book Bread and Jam for Frances by Russell Hoban is about precisely this dilemma. Frances – a young badger – does not want to eat anything except bread and jam. ‘How do you know what you’ll like if you won’t even try it?’ asks her father. Eventually, her parents give in to her demands for nothing but bread and jam. She is delighted. But over time, being excluded from what the rest of the family is eating makes her sad and she craves variety. One evening, Frances begs tearfully for some spaghetti and meatballs. Her parents express surprise, because they didn’t think she liked spaghetti. ‘How do you know what I’ll like if you won’t even try me?’ is her reply.

If liking is a consequence of familiarity, it follows that children are bound to like a narrower range of foods at first than adults, because they haven’t tried as many. Problems arise when parents interpret this temporary wariness as something permanent. This is an easy mistake to make. The key period for acquiring preferences is toddlerdom: from one to three. But this coincides with a period in the child’s life when they are most maddeningly, wilfully reluctant to try anything new. All children suffer from neophobia to a greater or lesser extent – a fear of new foods, often novel vegetables but also very commonly protein foods such as fish and meat. This reaches a peak between two and six. It probably evolved as a safety mechanism to protect us from toxins as we foraged in the wild. Now, unfortunately, it leads children away from the very foods they need to learn to like – vegetables and protein – and towards the comforting embrace of cakes, white bread and doughnuts.

As the name suggests, neophobia isn’t just a dislike of how something tastes: it is an active fear of tasting it. In many cases, neophobia can be broken down simply by feeding the food to the child numerous times – often as many as fifteen – until the child realizes they haven’t suffered any adverse consequences. See, the tomato didn’t kill you! See, it didn’t kill you again! Bit by bit dislike is lessened until one day it flips, almost comically, to enthusiasm. This has to be done over and over for each new ingredient. A child’s love of cantaloupe is no guarantee that they will like watermelon.

The biggest problem with using ‘mere exposure’ on children is that you first have to persuade them to try the food. Exposing a child to broccoli multiple times is easier said than done. As any parent who has ever tried to feed a recalcitrant toddler will know, the best-intentioned strategies often backfire. ‘Eat your vegetables and you can have a sweet’ is a dangerous game to play because it makes the child dislike the vegetables even more. Psychologists call this the over-justification effect.⁵¹ When a reward is offered for performing an activity, that activity is valued less. The child ends up loving sweets more, because they have become a prize.

Given that neophobia is a deep-seated fear that the unfamiliar food will cause you harm, it can help if the child witnesses someone else eating the food and surviving; preferably even enjoying it. I did not know that this was what I was doing, but after various futile attempts to get my daughter, then three, to eat something green other than cucumber, I hatched the idea of bringing her favourite doll to eat with us. This doll – a grubby-faced baby boy – sat at the table and proceeded to ‘eat’ green beans, as he oohed and ahhed with ecstasy (or rather, I did). It felt pretty lame, but one day my daughter begged to be given some of the baby doll’s green beans too and has loved them ever since. Another successful strategy is combining a scary new food with a familiar old one. Both children and adults are more likely to try something new when it is served with a familiar condiment – a blanket of ketchup, say, that renders the new food safe enough to try. But as the food psychologist John Prescott has written, no amount of ketchup will induce most children to try a plateful of spiders.⁵²

Most children get over the worst of their fear of new food by the age of six or seven. Up to this age, it is considered a normal stage of child development. Having conquered neophobia, they may flip over to neophilia: an ostentatious delight in novel flavours that can look suspiciously like showing off. My oldest child, the one who doesn’t like chocolate, is like this. His favourite foods change with capricious haste; dishes may please him at first, then bore him. He abhors plainness, grumbling that I always cook the same things for supper (charming!) and taking a macho delight in strongly flavoured condiments. When he was eight, we went to Rome, just the two of us. At a famous offal restaurant, he selected from the menu a dish called ‘artichokes with lamb’s hearts and all the organs in the vicinity’. And ate it too, with gusto.

For a significant minority, however, a terror of new food – or mixed-up food, or strange food or spicy food or food that just plain smells wrong – is never conquered. The numbers are high: it has been estimated that as many as a quarter of all adults are severely neophobic about what they eat. Fussiness in children is something we often joke about or laugh off. The cornflake boy was seen – outside his family, anyway – as a comic figure rather than a tragic one.

But living as a neophobic adult is no joke. I’ve met grown men and women who quietly confessed that they could not bring themselves to eat any vegetables. One said she only felt safe when eating reheated frozen Yorkshire puddings, the main thing her mother, an alcoholic, cooked for her. Even now, the sight of vegetables nauseated her. This woman wasn’t stupid. She had not failed to comprehend that vegetables are healthy. She got it; but the roots of her behaviour lay elsewhere, deep in the past.

Apart from the health implications of eating such a limited diet, it is socially awkward. Any meal in an unfamiliar setting is fraught with potential embarrassment. I spoke to another neophobic woman who said that whenever friends suggested a meal out, she had to call ahead to the restaurant to confirm that they could cook her a plain hamburger with absolutely no condiments. She ate no vegetables, though she was training herself slowly to like some fruits. When I asked why she disliked vegetables so much she laughed ruefully and said, ‘I think when I was about three, my mum got fed up with me being so fussy, so she decided to let me just have the things I liked.’ Which meant processed meats, chips and not much else.

The belief that tastes are a facet of personality – or genes – has dangerous consequences. If you think that children are born with certain inbuilt likes and dislikes – as fixed as eye colour – you may make no attempt to change them, because what’s the point? In a 2013 journal article called ‘Why Don’t They Like That? And Can I Do Anything about It?’ nutritionists interviewed sixty Australian parents about their children’s likes and dislikes.⁵³ They found that parents of children who had unhealthy eating habits were much more likely to think there was little parents could do to influence their offspring’s tastes, because children were just born to be difficult eaters or not.

The parents of healthy eaters made very different comments. They talked about how a child’s tastes were not ‘set in stone’. One of the mothers said it was possible to ‘educate’ the taste buds of children by exposing them to lots of different foods. Compared to the parents of unhealthy or neophobic eaters, parents of healthy eaters had a much stronger belief in their own power to influence a child’s likes and dislikes. Because they believed their actions had an impact on the children, these parents did their best to create a food environment where the children could develop enough healthy likes for a ‘balanced diet’. Conversely, the parents of the unhealthy eaters thought there was nothing they could do; and so, from the sound of things, they had more or less given up.

You could, of course, read this study in a different way. Not all children are equally easy to feed and there is undoubtedly a temperamental (and genetic) aspect to neophobia. Some toddlers are very much more reluctant to attempt new foods than others, no matter what parenting they receive. Maybe the parents of the healthy eaters chose to attribute their child’s good habits to their influence when really it was just luck (or genes). It’s easy to believe there is no such thing as genetic fussiness when your children eat well. When you are trapped in daily battles with a finicky toddler, enduring porridge thrown in the face and cauliflower on the floor, it can be irksome to listen to the smug parents whose children will ‘try anything – celeriac’s her favourite!’. Maybe the neophobic children really were harder to influence than the non-neophobic healthy eaters.

Nevertheless, there is strong evidence that the parents of the healthy eaters were right. Even if some of us take longer to warm up to vegetables than others, likes and dislikes are not predetermined. In most cases, it is perfectly possible not just to persuade children to eat vegetables – but to love them.

Dr Lucy Cooke spends her days trying to figure out how children’s dislike of vegetables can be reversed. Cooke’s research⁵⁴ – in collaboration with colleagues at University College London, notably Jane Wardle – makes her hopeful that our genetic inheritance for food preferences can be overcome. After all, she herself was once a child who didn’t like vegetables, and now she is a slim, confident person who positively enjoys healthy eating, although she tells me one day at a pavement café over toasted teacakes and mint tea that she does sometimes feel deprived to think of all the foods she could eat and doesn’t. ‘But one mustn’t say that!’

In Cooke’s view, the enterprise of weaning children onto solid food should be managed with a view to setting them up with healthy likes for life. When children actually enjoy vegetables – plus a range of whole foods from all the other nutrient groups – half the battles over dinner disappear. Most parents see the aim of feeding as getting as much wholesome food into a child as possible. We focus too much on short-term quantity – kidding ourselves that if they are pacified with enough baby rice they’ll sleep better – and not enough on building long-term tastes. ‘The only mums we see who talk about developing a child’s palate are French,’ in Cooke’s experience.

From four to seven months, it seems that there is a window when humans are extraordinarily receptive to flavour, but by following current guidelines on exclusive breastfeeding, parents tend to miss it.⁵⁵ Several studies have shown that when vegetables are introduced at this age, babies are more open-minded. It takes fewer exposures to persuade them to like a new flavour and the effects are long-lasting. When seven-month-old babies in Germany were exposed to a vegetable purée that they particularly disliked – such as spinach or green bean – it took only seven attempts for them to like it as much as their once-preferred carrot purée.⁵⁶ Two months later, all but 10 per cent of the children still enjoyed the once-hated vegetable, even though they had now reached an age of greater wariness. The flavour window is only fully open for a short time and seems to decline even from four to six months. A 2014 study found that when babies were introduced to a single vegetable at six months – pea purée – they ate significantly less of it than babies who were introduced to a range of purées at four months.⁵⁷

For this reason, Cooke disagrees with the 2001 directive from the World Health Organization (WHO) that said babies should be offered an exclusive diet of breast milk for six months, with no additional solid food. This WHO report forms the basis of official guidelines to mothers in most countries, even though the statistics it was based on were mostly from the developing world, where the risks of moving away from exclusive breastfeeding before six months – such as an increased chance of gastroenteritis and faltering growth – outweigh the benefits. In rich countries, however, the norm is for most mothers to stop breastfeeding, exclusive or otherwise, well before six months. In the UK just 1 per cent of mothers are still exclusively breastfeeding at six months after birth.⁵⁸ In the US it is 18.8 per cent.⁵⁹ The main effect of the official guidelines is to hold back many formula-fed babies from experiencing any flavour except for milk from four to six months. Here, the real risk is in producing children with limited tastes who will be set up for a lifetime of unhealthy eating. As so often, we fail to see the long-term picture.

It’s not that a four-month-old baby is likely to grow any better in the short term when their diet includes a spoonful here and there of veg. It’s that waiting until six months to wean is to miss two months in which a child could be tasting different vegetables every day, preparing them for a recognition – and hence liking – of those same vegetables at a later stage.

The second mistake parents make – and they are encouraged to do this by those baby feeding guides with their brightly organized charts of first foods – is starting children off with bland, honeyed tastes, such as carrot, butternut squash and sweet potato. Start with those vegetables that are naturally sweet, urges the UK’s bestselling author on baby food and save stronger flavours for later.⁶⁰ The really useful thing, however, would be to get a baby used to more bitter or challenging vegetables: cauliflower, courgette, spinach, broccoli, even sprouts. Weaning guides often advise sticking to a single vegetable for a whole week before switching – for fear of food allergies – but Cooke advocates lots of variety and daily changes to maximize exposure before the child enters the age of neophobia. When novel vegetables are offered to a six-month-old, the baby will often make the most dramatic expressions of horror and woe, screwing up the mouth and nose in ways that, on an adult face, would suggest torture. The hardest thing for parents is to press on with offering the food. ‘We have to persuade mums to ignore the face,’ explains Cooke. Unlike Clara Davis, who wanted to see how babies would eat away from parental influence, Cooke has devised pragmatic experiments recognizing that parents are part of the feeding process. Her starting point is always looking at what parents already do when feeding children and trying to find evidence-based techniques to help them do it better.

What if you have missed the ‘flavour window’ and are now attempting to feed a toddler who fears anything green? Is all hope lost? Cooke and colleagues found that even with school-age children, there was a great deal that could be done to change apparently fixed hatreds of certain foods. Their first revelation was that much of what manifests itself as fussiness is a response to the stressful situation of mealtimes. It can get to the extreme point where lunch itself is a ‘dislike’ – the pressure, the heightened emotions – no matter what is served. Cooke found that if parents could do tasting sessions with children outside meals, it could take emotion out of it. In addition, they only asked children to try pea-sized amounts of food, which reduces the feeling of pressure. ‘The demands on the child have to be very low.’ A whole plate of cauliflower is a horrible prospect if you don’t like it. A minuscule fragment might just be OK.

Cooke helped devise a new system for encouraging more vegetable ‘likes’ called Tiny Tastes.⁶¹ It was trialled in both schools and in homes and has proved remarkably effective in making children actually like raw vegetables such as carrot, celery, tomato, red pepper and cucumber. I used the scheme on my own youngest child – then aged four – and was startled how quickly it turned him from someone who said ‘yuck’ when he heard the word cabbage to a happy nibbler of raw green leaves. It works like this. The parent and child together select a vegetable that the child currently moderately dislikes (as opposed to feeling deeply revolted by). Each day for ten to fourteen days, not at dinnertime, you offer them a pea-sized amount. If they taste it – licking counts, it doesn’t have to be swallowed – they get a tick in a box and a sticker. If not, it’s no big deal; there is always tomorrow.

The usefulness of Tiny Tastes is that it provides a non-stressful way to enact the multiple exposures that we seem to need to develop new tastes. In our house, it changed the whole conversation around mealtimes, from one of stress and anxiety to something – mostly – more positive and mellow. Because he chose the vegetable himself, my child seemed to feel less trapped. Plus, he really likes stickers. Lucy Cooke said that before they started using stickers in their experiments, there would always be a few children who would refuse to take part; with stickers, participation went up to 100 per cent. Cooke’s research overturns the previous orthodoxy that offering rewards for eating would make children like the food even less. Her hunch is that rewards only work first when they are not themselves food and second when the child feels they have genuinely worked for them. If you reward someone for eating a healthy food that they already like, it confuses them. But it takes a real effort for a child who dislikes raw red pepper to put that first morsel in their mouth, hence they feel they deserve the sticker.

This approach to creating new, better likes sounds almost too good – too simple – to be true. For one thing, it only addresses vegetables, which is a good place to start, but there’s a lot more to a healthy diet than just greens. For many children, it is the protein foods – eggs, meat, fish – that are the hardest to love. Tiny Tastes also presumes that a child will willingly cooperate, once stickers are proposed. What about the hardcore food refuseniks? Some people have very definite dislikes with their roots in complex conditions, which surely can’t be wished away with a sticker.

When children have learning difficulties or other disabilities, one of the many daily tasks they often tussle with is eating. Children who are slow to speak also tend to be slow to master the skills of eating, because there is a strong relationship between the muscle control needed for language and for chewing and swallowing. Eating can also become a problematic business for those whose condition involves rigid behaviours and routines. Those on the autistic spectrum are far more likely to have a wide range of problems with food than other children. It’s been estimated that 75 per cent of children diagnosed with autism have severe feeding difficulties.⁶² They may demand exclusively ‘yellow’ food (crisps, corn, biscuits, popcorn, fried chicken), or refuse to eat a meal unless none of the components are touching. Above all, autistic children are likely to have a very narrow range of foods that they find acceptable.⁶³

Jim,^fn1 aged three and a half, was an autistic boy with serious eating problems by the time he arrived at the Penn State Hershey Medical Center in Pennsylvania. He ate only two foods, toasted cheese sandwiches and hotdogs, supplemented with frequent glasses of milk. In addition, Jim tended to be disruptive at mealtimes, tantrumming, crying, acting out, refusing food from even his limited repertoire.⁶⁴

But Jim was doing well compared to Kim, a five-year-old autistic girl referred to the same clinic. For a while, Kim too had eaten a limited diet of hotdogs, peanut butter, bacon, chocolate, eggs and toast. She too would cry, tantrum and throw food at mealtimes. After an illness, though, she stopped eating altogether and for six months had been completely dependent on feeding through a gastrostomy tube.

Most parents would feel overwhelmed at the thought of feeding these children and somehow broadening their horizons. I know I would. Food refusal is demoralizing at the best of times; all the more so when you are dealing with the other challenges of caring for an autistic child. If a child disliked most foods to the point that they provoked tears and rage, it would be very hard to bring yourself to do anything other than sigh and make another toasted cheese sandwich.

Jim and Kim sound like two hopeless cases. But they weren’t. Within two weeks of intensive treatment at the centre, Jim’s repertoire of foods had increased from three to sixty-five. Kim, meanwhile, would now eat forty-nine different foods and no longer needed the feeding tube. This huge increase in ‘likes’ (and decrease in ‘dislikes’) was achieved not through any magic but simply through a more systematic and intensive version of Lucy Cooke’s Tiny Tastes system.

Therapists at the clinic engaged the children in many repeated taste sessions to expose them to pea-sized amounts of novel foods in the course of the day. Unlike with Tiny Tastes, the therapists added in an ‘escape prevention’ element: the child was told ‘when you take your bite, you can go and play’ and were not allowed to leave the room until the bite was taken. If they screamed or cried, this was ignored, but if they ate the pea-sized bite, they were praised. There were also ‘probe meals’ at which larger quantities of the new foods were offered – three tablespoons of three different foods – with a ten-minute time limit and no requirement to eat the food.

The results of this experiment are astonishing. To go from being fed by a tube to being able to eat forty-nine different foods is life-changing, for the whole family. A three-month follow-up showed that Jim and Kim had not lost the majority of their new likes at home. They had not slipped into the old unhappy mealtimes of before. Food was no longer a trauma to them. Both sets of parents were continuing to offer the children taste sessions outside mealtimes. Jim’s range of foods was now fifty-three. This large repertoire of foods was all the more impressive considering that Jim’s parents had decided to become vegetarian since the start of the intervention, the sort of change that autistic children often find unsettling. Kim’s range of foods was still forty-seven. In place of a tube, she was now enjoying a wide range of different flavours and textures, without tears or rage. Autism goes along with restricted social interaction. Yet Kim’s new likes placed her back in the social world of the family dinner table.

Similar work is being done by therapists at specialist feeding clinics across the world, although Keith Williams, head of the feeding clinic at the Penn State Hershey Medical Center, says that these methods are by no means standard practice. Too many feeding therapists still treat limited eaters such as Jim and Kim by offering them whole platefuls of disliked food and hoping they will suddenly decide to eat it. But when these interventions succeed, they show what huge potential there is for changing our likes and dislikes for the better through a change to our eating environment. No one is doomed to like nothing but cheese sandwiches and hotdogs. If it’s possible to train a severely autistic three-year-old to love fifty-three different nutritious foods, there’s hope for us all.

The trouble is, though, that most of our food environment influences us in an opposite direction. Every day, children are exposed to messages – whether on giant hoardings and TV ads or from looking in friends’ lunchboxes – telling them that they should like the very foods that will do them the most harm.

Karl Duncker’s 1930s experiments on children’s likes and dislikes are much less well known than Clara Davis and her feeding orphanage. But they offer just as great an insight into how our tastes are formed, almost in spite of ourselves, by forces we are only dimly aware of. While Davis was interested in what tastes look like stripped of the normal social influences, Duncker wanted to pinpoint how those influences actually work.

In 1936 Duncker (born in Leipzig in 1903) was a promising young Gestalt psychologist exiled from Nazi Germany – where his parents were prominent communists – to Britain where he continued his work. One of his great philosophical interests was pleasure and what causes it. His definition of the pleasure of anticipation was a child who ‘has been told that he is soon to have a piece of candy … glowing all over with happiness’. In one of his papers, Duncker asked why eating a fine juicy beefsteak could cause such delight; he decided that it wasn’t just that it took away the pain of hunger. It was the sensory enjoyment of biting into it, and the feeling it gave that ‘life is grand’.⁶⁵

On arrival in Britain, Duncker set himself the task of investigating the role of social suggestion in forming food preferences. Given that likes and dislikes varied to an ‘astounding degree’ among different cultures, he realized that there must be a process of social influence at work. His mission was to unravel the psychological processes by which likes were formed.

Duncker’s experiments involved children from Somers Town nursery school in London NW1, which was then a poor district of London.⁶⁶ The first experiment was a simple one. Boys and girls aged between two and five were asked to make a food selection from carrots, bananas, nuts, apples, bread and grapes. What Duncker found was that children were far more likely to select the same foods as one another if they made their choice in the presence of other children, than if they were alone. For children younger than twenty-seven months there was a wonderful ‘social indifference’: ‘when they had fixed their minds upon the food, nothing else seemed to exist.’ Above that age, however, there was a marked tendency to copy the likes of other children, especially if the child who selected first was just a little older. There was one pair of girls where one was an extroverted five and the other a shy four. Before choosing her food, ‘B would always send some furtive glances over to A as if for reassurance’.

We’ve all seen this kind of peer influence at work. If you offer a snack to a group of young girls, they will often tie themselves in knots second-guessing what the others will go for before making up their own mind. You don’t want to be a lone wolf eating popcorn when everyone else has opted for toast. Duncker’s findings about social suggestion when eating have since been confirmed by at least sixty-nine separate experiments.⁶⁷ This is a very robust phenomenon. Depending on the influence of those who share our meals, we may eat faster or slower; we choose different foods; we manage larger or smaller portions.

Duncker’s second experiment was more dramatic. He took two substances. One was a white chocolate powder flavoured with lemon – a very luxurious commodity in 1930s Britain and ‘decidedly pleasant’. The other was valerian sugar coloured brown, valerian being a herbal root traditionally used as a sedative: a very bitter and medicinal flavour that Duncker called ‘rather unpleasant’. He then asked the nursery teacher to read the children a story about a hero, Micky, a little field mouse, who hates one food – ‘hemlock’ – and loves another – ‘maple sugar’. When Micky discovers maple sugar in a tree, he realizes he has never ‘tasted such good stuff before’. But the hemlock bark is ‘sour and disgusting’.

After the story, the children were then asked to taste some actual ‘hemlock’ – which was really the delicious white chocolate powder; and ‘maple sugar’ – which was really the unpleasant valerian sugar. The deception did not exactly work. Many of the children recognized that the ‘hemlock’ was really chocolate. Yet when asked to choose which substance they preferred, 67 per cent of them opted for the nasty-tasting ‘maple sugar’ because of the positive associations in the story (only 13 per cent chose it in a control group with no story).

Can our likes and dislikes really be so easily influenced? Apparently so. Duncker’s experiment shows that a simple story is enough to make children forget – for a time – that they like chocolate. For Duncker himself, having witnessed Hitler’s rise to power, it was no surprise that human beings are suggestible in their ‘likes’ or that social forces can make them suppress their natural impulses. At the time Karl Duncker was doing his peaceful experiments with children and chocolate, his younger brother Wolfgang was living a precarious life in exile in Moscow; he was arrested during the Great Purges of 1938 and died in the Gulag. Duncker himself had lost his academic position in Berlin in 1935 for having once been married to a Jewish woman.⁶⁸ ‘If educated adults,’ wrote Karl Duncker, ‘can be made to discard their ingrained preferences because the leader has contrary ones, why should children prove [harder to influence] – even in such a vital domain as food?’⁶⁹

Given his background, Duncker had a strong sense of how those with power manipulate the powerless. To him, a child being manipulated to change their ingrained food likes was in a similar position to the population of Nazi Germany.

Duncker’s findings are deeply worrying. If just one story about a not very inspiring mouse hero could make children change their likes to such a degree, what are the effects of a daily barrage of advertising stories, in which godlike athletes are shown drinking sugary beverages and the least nutritious cereals are those with the cutest characters on the box? ‘Don’t trust that tiger! He’s a bad tiger!’ I used to tell my son as we walked down the cereal aisle.

What can any one of us do in the face of such social pressure? Duncker offered himself up as an example of how individuals could train themselves to new likes, despite their social prejudices and circumstances, through a kind of ‘inner reorganisation’. When he arrived in Cambridge from Germany, Duncker was appalled by the prevalence of something called ‘salad cream’: a sharp condiment beloved in the British Isles that has the texture of mayonnaise but the acrid taste of spirit vinegar. Like many mass-market foods, it has a devoted following among those reared on it, but to Duncker, who wasn’t prepared for the taste, salad cream came as quite a shock.

Suffice it to tell just one personal experience. When I first came to England, I was made to understand that raw green salad leaves could be made into ‘salad’ with the aid of a bottled substance of yellowish color, called salad dressing. It looked like mayonnaise; I expected mayonnaise – and I dare say I was deeply disappointed. No, I did not like it. But as I did not like raw leaves either, I was therefore prompted to adopt the most favorable and adventurous attitude. I tried again, and I still remember the day when suddenly I discovered that this was not an unpleasant variant of mayonnaise but a kind of mustard which was not unpleasant at all. Thus by accentuating the mustard potentiality and suppressing the non-mayonnaise aspect, I came to like it.⁷⁰

Like Lucy Cooke, Duncker knew that there is huge scope for changing our likes and dislikes: not all of them, for sure, but enough to make the difference between a good diet and a bad one. Whether you are a PROP taster or not; autistic or not; neophobic or not; fussy or not; a foreigner or not; genes are never the final reason why you like the particular range of foods you do. When a boy likes nothing but cornflakes, it says less about him than it does about the world he lives in.

It would help if we stopped seeing our personal likes as such a deep and meaningful part of our essence. There are many things about ourselves we cannot change, but the majority of food likes do not fall into this category. Our tastes are learned in the context of immense social influences, whether from our family, our friends, or the cheery font on a bottle of soda. Yet it’s still possible, as Duncker showed, to carve out new tastes for ourselves. We can put the impressionable nature of our likes to good use. If we expose ourselves enough times to enough different foods, we may find, like Duncker, that the flavours we once disliked have now miraculously become likeable.

In Duncker’s case, sadly, taking what he called a ‘favourable and adventurous’ attitude to food was easier than taking a favourable attitude to life. By the time he was doing his experiment with children and white chocolate, he had been suffering from deteriorating mental health for the best part of a decade. Duncker missed life in Berlin, but knew he could never return while the Nazis were in power. Unlike his tastes in salad, this situation was intractable. In 1938 he emigrated from Britain to the United States to take up a job at Swarthmore College. It was there he committed suicide in 1940, at the age of thirty-seven.⁷¹