The Power of Their Peers

By ROBERT WRIGHT

Psychologists can call off their century-long search for the key to rearing a good child--not because they've found it but because it doesn't exist. At least, that is the thesis of a soon-to-be-published, destined-for-controversy book, The Nurture Assumption (Free Press; 480 pages). Its author, Judith Rich Harris, states baldly that parents do not have "any important long-term effects on the development of their child's personality."

Harris is not saying that the genetic lottery sets a child's destiny. Around half of the difference in personality among kids, she notes, is unaccounted for by genetics. Rather, she is saying that the crucial environmental influence is outside the home.

There kids absorb the values of peers and find a niche in the local ecology. They become known as tough or nice or wacky or wicked, and personality starts to harden. Granted, parents can shape behavior within the home. But in the wider world, Harris argues, the child is a different person, and there lie the roots of the budding adult.

Harris' clever and witty book makes this argument with power, but that's partly because she doesn't brake for subtleties. A classic 1928 study, she writes, found that children who violated rules at home "were not noticeably more likely than anyone else to cheat on a test at school or in a game on the playground." Actually, that study did find some correlation between honesty inside and outside the home. And psychologist Douglas Jackson has reanalyzed the data with modern statistical techniques and found a very high correlation.

To be sure, pop-psych notions about how you create a good kid--about some simple, magical parenting style--were due for the thrashing Harris gives them. Behavioral geneticists have learned that identical twins reared together are scarcely more alike than identical twins reared apart. This and other data suggest that the "shared environment" of siblings--including the overall household atmosphere and child-rearing tenets that parents apply to all their kids--have little straightforward effect on personality.

Rather, say behavioral geneticists, the "non-shared" environment is where the action is. Jimmy and Johnny find different peer groups at school, or different niches in a single peer group; Jimmy becomes valedictorian, Johnny becomes trouble. What's a mother to do? Non-shared environments outside the home, not parents, get the blame in Harris' theory.

But non-shared environments can also exist inside the home. Maybe, for example, parents treat siblings differently--doting on Jimmy and screaming at Johnny, say--and that is why Johnny went bad. If Harris is to demolish the nurture assumption, she must somehow dismiss such dynamics.

She tries. She pungently punctures various arguments linking parental treatment to child behavior. Maybe mommy's screaming at Johnny didn't cause his misbehavior, as some scholars naively assume, but rather was caused by it. Maybe. Still, maybe the screaming made things worse. Or maybe mommy was subtly favoring Jimmy all along. How would you know for sure? The more puncturing of arguments Harris does, the more you realize that the whole issue of non-shared environments in the home is disconcertingly complex, nearly opaque to science.

One of the few exceptions is birth order. (Maybe younger siblings get treated differently by parents, or face some other "microenvironmental" effect, such as getting slugged by older siblings.) Harris tries at length to debunk correlations between birth order and personality, but even if she succeeded, it wouldn't much matter. Birth order is but one of countless possible reasons that parents might treat kids differently. Most others are nearly impossible to study--and in any event are not well studied. Nonetheless, Harris, having grappled with the tip of the iceberg, declares victory.

A boy in Arkansas shoots schoolmates; his younger brother doesn't. Why? Did alienation at school reach critical mass because he felt less loved at home than his brother? Did schoolyard rejection make him morose, hence impervious to a parenting style that worked well enough with his brother? Is that the key--calibrating your parenting style to your kids' different needs? We just don't know.

In between too-breezy formulations of her thesis ("parents count zilch"), Harris makes key qualifications. She recognizes that moral attitudes are more malleable than personality traits. She even thinks there are a few things parents can do for their children. And she argues that good teachers can matter, shaping the ethos of a child's peer group.

Harris' core, convincing message--that many parents wildly overestimate their influence--may usefully calm some nerves in this age of high-anxiety parenting. But it may also do the opposite. These days much parental fretting is already going into the shaping of peer groups and their context. Which private school? Soccer on Saturday or French lessons? Birthday party at Marva Tots or the Discovery Zone?

Relax. Science hasn't answered these questions either.