Читать книгу SNAP! - Gary Small - Страница 9

Doctors and other experts have long theorized that our personalities are formed in early childhood and remain consistent throughout life. Research has suggested that by first grade, children have already developed personality traits that can predict their adult behavior.

When I began to study psychiatry, I delved deeper into various theories of personality formation. Sigmund Freud speculated that each child progresses through different stages of psychosexual development, which shape that person’s long-term disposition. Erik Erickson described eight stages of developmental crises that mold personality. He speculated that an individual’s insecurity stemmed from an impasse during one of those eight stages, such as young adulthood, when struggles with intimacy versus isolation are common. Behaviorists like B. F. Skinner and John Watson held that personality stems from interactions between the individual and the environment. Carl Rogers, Abraham Maslow, and other humanist theorists emphasized free will and experience as the driving forces that form personality.

John Bowlby theorized that an infant’s early attachment or basic need for closeness with their first caregiver (usually the mother) was the basis for that child’s long-term adaptive strategies to relationships, which can influence personality traits. Bowlby posited that a baby who received caring and consistent parenting early in life would form a secure attachment and grow to be an independent, self-reliant, and curious person. However, infants who don’t form a secure attachment may become needy, insecure, and distrustful of others and may have difficulty making friends.

During my psychiatry training, I found these and other theories to be interesting, but I conjectured that a person’s early life experiences could not be the whole story. Even though I was taught to understand personality at a psychological level, I presumed that genetics must come in to play. Studies have shown that identical twins who share 100 percent of the same DNA are significantly more likely to share personality traits than fraternal twins who share only 50 percent of their DNA. This early work and later studies made clear that our genes do affect our personalities. However, the relationship is complex, and no specific personality gene has yet been discovered.

Research indicates that the heritability of our personalities—or what proportion of our character is inherited from our parents—varies from about 40 to 60 percent depending on the particular personality trait being considered. That means that for the average person, about 50 percent of what determines their personalities is not genetic—each of us may have much more control over our personalities than we realize.