Сьюзан Кейн - Quiet [The Power of Introverts in a World That Can't Stop Talking]

Kagan tells me about the time he watched a fellow scientist give a wonderful talk at a conference. Afterward, the speaker asked if they could have lunch. Kagan agreed, and the scientist proceeded to tell him that he gives lectures every month and, despite his capable stage persona, is terrified each time. Reading Kagan’s work had had a big impact on him, however.

“You changed my life,” he told Kagan. “All this time I’ve been blaming my mother, but now I think I’m a high-reactive.”

So am I introverted because I inherited my parents’ high reactivity, copied their behaviors, or both? Remember that the heritability statistics derived from twin studies show that introversion-extroversion is only 40 to 50 percent heritable. This means that, in a group of people, on average half of the variability in introversion-extroversion is caused by genetic factors. To make things even more complex, there are probably many genes at work, and Kagan’s framework of high reactivity is likely one of many physiological routes to introversion. Also, averages are tricky. A heritability rate of 50 percent doesn’t necessarily mean that my introversion is 50 percent inherited from my parents, or that half of the difference in extroversion between my best friend and me is genetic. One hundred percent of my introversion might come from genes, or none at all—or more likely some unfathomable combination of genes and experience. To ask whether it’s nature or nurture, says Kagan, is like asking whether a blizzard is caused by temperature or humidity. It’s the intricate interaction between the two that makes us who we are.

So perhaps I’ve been asking the wrong question. Maybe the mystery of what percent of personality is nature and what percent nurture is less important than the question of how your inborn temperament interacts with the environment and with your own free will. To what degree is temperament destiny?

On the one hand, according to the theory of gene-environment interaction, people who inherit certain traits tend to seek out life experiences that reinforce those characteristics. The most low-reactive kids, for example, court danger from the time they’re toddlers, so that by the time they grow up they don’t bat an eye at grown-up-sized risks. They “climb a few fences, become desensitized, and climb up on the roof,” the late psychologist David Lykken once explained in an Atlantic article. “They’ll have all sorts of experiences that other kids won’t. Chuck Yeager (the first pilot to break the sound barrier) could step down from the belly of the bomber into the rocketship and push the button not because he was born with that difference between him and me, but because for the previous thirty years his temperament impelled him to work his way up from climbing trees through increasing degrees of danger and excitement.”

Conversely, high-reactive children may be more likely to develop into artists and writers and scientists and thinkers because their aversion to novelty causes them to spend time inside the familiar—and intellectually fertile—environment of their own heads. “The university is filled with introverts,” observes the psychologist Jerry Miller, director of the Center for the Child and the Family at the University of Michigan. “The stereotype of the university professor is accurate for so many people on campus. They like to read; for them there’s nothing more exciting than ideas. And some of this has to do with how they spent their time when they were growing up. If you spend a lot of time charging around, then you have less time for reading and learning. There’s only so much time in your life.”

On the other hand, there is also a wide range of possible outcomes for each temperament. Low-reactive, extroverted children, if raised by attentive families in safe environments, can grow up to be energetic achievers with big personalities—the Richard Bransons and Oprahs of this world. But give those same children negligent caregivers or a bad neighborhood, say some psychologists, and they can turn into bullies, juvenile delinquents, or criminals. Lykken has controversially called psychopaths and heroes “twigs on the same genetic branch.”

Consider the mechanism by which kids acquire their sense of right and wrong. Many psychologists believe that children develop a conscience when they do something inappropriate and are rebuked by their caregivers. Disapproval makes them feel anxious, and since anxiety is unpleasant, they learn to steer clear of antisocial behavior. This is known as internalizing their parents’ standards of conduct, and its core is anxiety.

But what if some kids are less prone to anxiety than others, as is true of extremely low-reactive kids? Often the best way to teach these children values is to give them positive role models and to channel their fearlessness into productive activities. A low-reactive child on an ice-hockey team enjoys his peers’ esteem when he charges at his opponents with a lowered shoulder, which is a “legal” move. But if he goes too far, raises his elbow, and gives another guy a concussion, he lands in the penalty box. Over time he learns to use his appetite for risk and assertiveness wisely.

Now imagine this same child growing up in a dangerous neighborhood with few organized sports or other constructive channels for his boldness. You can see how he might fall into delinquency. It may be that some disadvantaged kids who get into trouble suffer not solely from poverty or neglect, say those who hold this view, but also from the tragedy of a bold and exuberant temperament deprived of healthy outlets.

The destinies of the most high-reactive kids are also influenced by the world around them—perhaps even more so than for the average child, according to a groundbreaking new theory dubbed “the orchid hypothesis” by David Dobbs in a wonderful article in The Atlantic . This theory holds that many children are like dandelions, able to thrive in just about any environment. But others, including the high-reactive types that Kagan studied, are more like orchids: they wilt easily, but under the right conditions can grow strong and magnificent.

According to Jay Belsky, a leading proponent of this view and a psychology professor and child care expert at the University of London, the reactivity of these kids’ nervous systems makes them quickly overwhelmed by childhood adversity, but also able to benefit from a nurturing environment more than other children do. In other words, orchid children are more strongly affected by all experience, both positive and negative.

Scientists have known for a while that high-reactive temperaments come with risk factors. These kids are especially vulnerable to challenges like marital tension, a parent’s death, or abuse. They’re more likely than their peers to react to these events with depression, anxiety, and shyness. Indeed, about a quarter of Kagan’s high-reactive kids suffer from some degree of the condition known as “social anxiety disorder,” a chronic and disabling form of shyness.

What scientists haven’t realized until recently is that these risk factors have an upside. In other words, the sensitivities and the strengths are a package deal. High-reactive kids who enjoy good parenting, child care, and a stable home environment tend to have fewer emotional problems and more social skills than their lower-reactive peers, studies show. Often they’re exceedingly empathic, caring, and cooperative. They work well with others. They are kind, conscientious, and easily disturbed by cruelty, injustice, and irresponsibility. They’re successful at the things that matter to them. They don’t necessarily turn into class presidents or stars of the school play, Belsky told me, though this can happen, too: “For some it’s becoming the leader of their class. For others it takes the form of doing well academically or being well-liked.”