Shyness, Sadness, Curiosity, Joy. Is It Nature Or Nurture?

IF ANY CHILD SEEMED DESTINED TO GROW UP afraid of her shadow and just about anything else that moved, it was 2-year-old Marjorie. She was so painfully shy that she wouldn't talk to or look at a stranger. She was even afraid of friendly cats and dogs. When Jerome Kagan, a Harvard professor who discovered that shyness has a strong genetic component, sent a clown to play with Marjorie, she ran to her mother. "It was as if a cobra entered that room;' Kagan says. His diagnosis: Marjorie showed every sign of inherited shyness, a condition in which the brain somehow sends out messages to avoid new experiences. But as Kagan continued to examine her over the years, Marjorie's temperament changed. When she started school, she gained confidence from ballet classes and her good grades, and she began to make friends. Her parents even coaxed her into taking horseback-riding lessons. Marjorie may have been born shy, but she has grown into a bubbly second grader.

For Marjorie, then, biology--more specifically, her genetic inheritance--was not her destiny. And therein lies our tale. In the last few years scientists have identified genes that appear to predict all sorts of emotional behavior, from happiness to aggressiveness to risk-taking. The age-old question of whether nature or nurture determines temperament seems finally to have been decided in favor of Mother Nature and her ever-deepening gene pool. But the answer may not be so simple after all. Scientists are beginning to discover that genetics and environment work together to determine personality as intricately as Astaire and Rogers danced. "If either Fred or Ginger moves too fast, they both stumble," says Stanley Greenspan, a pediatric psychiatrist at George Washington University and the author of "The Growth of the Mind." "Nature affects nurture affects nature and back and forth. Each step influences the next." Many scientists now believe that some experiences can actually alter the structure of the brain. An aggressive toddler, under the right circumstances, can essentially be rewired to channel his energy more constructively. Marjorie can overcome her shyness--forever. No child need be held captive to her genetic blueprint. The implications for child rearing-and social policy-are profound.

While Gregor Mendel's pea plants did wonders to explain how humans inherit blue eyes or a bald spot, they turn out to be an inferior model for analyzing something as complex as the brain. The human body contains about 100,000 genes, of which 50,000 to 70,000 are involved in brain function. Genes control the brain's neurotransmitters and receptors, which deliver and accept mental messages like so many cars headed for their assigned parking spaces. But there are billions of roads to each parking lot, and those paths are highly susceptible to environmental factors. In his book "The New View of Self," Dr. Larry Siever, a psychiatry professor at Mount Sinai Medical Center, writes about how the trauma of the Holocaust caused such intense genetic scrambling in some survivors that their children inherited the same stress-related abnormalities. "Perhaps the sense of danger and uncertainty associated with living through such a time is passed on in the family milieu and primes the biological systems of the children as well," says Siever. He added that that might explain why pianist David Helfgott, the subject of the movie "Shine," had his mental breakdown.

A gene is only a probability for a given trait, not a guarantee. For that trait to be expressed, a gene often must be "turned on" by an outside force before it does its job. High levels of stress apparently activate a variety of genes, including those suspected of being involved in fear, shyness and some mental illnesses. Children conceived during a three-month famine in the Netherlands during a Nazi blockade in 1945 were later found to have twice the rate of schizophrenia as did Dutch children born to parents who were spared the trauma of famine. "Twenty years ago, you couldn't get your research funded if you were looking for a genetic basis for schizophrenia, because everyone knew it was what your mother did to you in the first few years of life, as Freud said," says Robert Plomin, a geneticist at London's Institute of Psychiatry. "Now you can't get funded unless you're looking for a genetic basis. Neither extreme is right, and the data show why. There's only a 50 percent concordance between genetics and the development of schizophrenia."

Scientists have been devoting enormous energy to determining what part of a given character trait is "heritable" and what part is the result of socialization. Frank Sulloway's book "Born to Rebel," which analyzes the influence of birth order on personality, opened a huge window on a universal-and largely overlooked--environmental factor. But that's abroad brushstroke. Most studies focus on remarkably precise slivers of human emotions. One study at Allegheny University in Pennsylvania found that the tendency for a person to throw dishes or slam doors when he's angry is 40 percent heritable, while the likelihood a person will yell in anger is only 28 percent heritable. The most common method for determining these statistics is studying twins. If identical twins are more alike in some way than are fraternal twins, that trait is believed to have a higher likelihood of being inherited. But the nature-nurture knot is far from being untied.

The trick, then, is to isolate a given gene and study the different ways environment interacts with it. For instance, scientists believe that people with the longer variety of a dopamine-4 receptor gene are biologically predisposed to be thrill seekers. Because the gene appears to make them less sensitive to pain and physical sensation, the children are more likely to, say, crash their tricycles into a wall, just to see what it feels like. "These are the daredevils," says Greenspan. But they need not be. Given strict boundaries, Greenspan says, thrill-seeking kids can be taught to modulate and channel their overactive curiosity. A risk-taking child who likes to pound his fist into hard objects can be taught games that involve hitting softly as well. "If you give them constructive ways to meet their needs," says Greenspan, "they can become charismatic, action-oriented leaders."

Shyness has been studied perhaps more than any other personality trait. Kagan, who has monitored 500 children for more than 17 years at Harvard, can detect telltale signs of shyness in babies even before they're born. He's found that the hearts of shy children in the womb consistently beat faster than 140 times a minute, which is much faster than the heartbeats of other babies. The shy fetus is already highly reactive, wired to over monitor his environment. But he can also outgrow this predisposition if his parents gently but firmly desensitize him to the situations that cause anxiety, such as encouraging him to play with other children or, as in Marjorie's fear of animals, taking her to the stables and teaching her to ride a horse. Kagan has found that by the age of 4, no more than 20 percent of the previously shy children remain that way.

Will the reprogramming last into adulthood? Because evidence of the role of genes has been discovered only recently, it's still too early to tell. But studies of animals give some indication. Stephen Suomi at the National Institute of Child Health and Human Development works with rhesus monkeys that possess the same genetic predisposition to shyness that affects humans. He's shown that by giving a shy monkey to a foster mother who is an expert caregiver, the baby will outgrow the shyness. Even more surprising, the once shy monkey will become a leader among her peers and an unusually competent parent, just like P the foster more. Though she will likely pass along her shyness genes to her own child, she will teach it how to overcome her predisposition, just as she was taught. And the cycle continues--generations of genetically shy monkeys become not just normal, but superior, adults and parents. The lesson, says Snomi: "You can't prejudge anyone at birth. No matter what your genetic background, a negative characteristic you're born with may even turn out to be an advantage."

But parents aren't: scientists, and it's not always easy to see how experience can influence a child's character. A baby who smiles a lot and makes eye contact is, in part, determining her own environment, which in turn affects her temperament. As her parents coo and smile and wrinkle their noses in delighted response, they are reinforcing their baby's sunny disposition. But what about children who are born with low muscle tone, who at 4 months can barely hold up their own heads, let alone smile? Greenspan has discovered that mothers of these kids smile at the baby for a while, but when the affection isn't returned, they give up. And so does the baby, who over time fails to develop the ability to socialize normally. "If you move in the wrong patterns, the problem is exacerbated," Greenspan says. He has found that if parents respond to nonsmiling babies by being superanimated-like Bob Barker hosting a game show--they can engage their child's interest in the world.

The ramifications of these findings clearly have the potential to revolutionize child-rearing theory and practice. But to an uncertain end. "Our society has a strong belief that what happens in childhood determines your fate. If you have a happy childhood, everything will be all right. That's silly," says Michael Lewis, director of the Institute for the Study of Child Develop-merit in New Jersey and the author of "Altering Fate." Lewis estimates that experience ultimately rewrites 90 percent of a child's personality traits, leaving an adult with only one tenth of his inborn temperament. "The idea that early childhood is such a powerful moment to see individual differences in biology or environment is not valid," he says. "We are too open to and modifiable by experience." Some scientists warn that attempting to reprogram even a narrow sliver of childhood emotions can prove to be a daunting task, despite research's fascinating new insights. "Children are not a 24-hour controlled experiment," says C. Robert Cloninger, a professor of psychiatry and genetics at the Washington University School of Medicine in St. Louis. "If you put a child in a Skinner box, then maybe you could have substantial influence." So, mindful of the blinding insights of geneticists and grateful for the lingering influences of environment, parents must get on with the business of raising their child, an inexact science if ever there was one.

61% of all parents believe that differences in behavior between girls and boys are not inborn but a result of the way they're raised.

78% of those polled who are in two-parent families say that they share equally when it comes to setting rules for their young child.

Shyness, Sadness, Curiosity, Joy. Is It Nature Or Nurture? | News