You feel depressed. Things haven't turned out the way you wanted. You've never had the confidence to follow through with your plans. The reasons, of course, are well known. You were ignored as a child. Your brother got all the attention. Your mom and dad weren't home when you needed them.

Not according to Judith Rich Harris, author of The Nurture Assumption: Why Children Turn Out the Way They Do. In this controversial work, Harris examines Western society's widely held belief that a child's personality is determined by two factors, nature (heredity) and nurture (child-rearing). Although there are strong indications that genes influence personality, she finds no good evidence that child-rearing styles do so. Harris claims that researchers have never seriously questioned the dominance of the family in influencing a child's life, an unstated assumption she refers to as "the nurture assumption."

Many of us believe that parents wield the greatest influence on a child's life. Children want to grow up to be like their parents. A child properly nurtured and cared for by the parents will grow to achieve all that his or her abilities will allow. And a troublemaking child likely had a poor upbringing.

Harris goes to some length to demonstrate that, though these are popular opinions, they are not supported by scientific evidence. She describes how many carefully controlled studies have failed to demonstrate any significant influence from different parenting styles. Furthermore, she contends that studies that do show such influences have failed to separate the effects of parenting style from those of genetics, economic status, neighborhood, or peer group.

These conclusions will not surprise at least one group of people - behavioral geneticists. Studies of identical and fraternal twins have shown that nearly half of the variation in our personalities can be attributed to genetics. These studies also show only a limited contribution from "shared environmental influences," that is, growing up in the same home. As T.J. Bouchard wrote in Science back in 1994, "This is now a well-replicated finding in behavior genetics, and its implications are straightforward. The similarity we see in personality between biological relatives is almost entirely genetic in origin." But what nongenetic factors are responsible for determining personality? And why don't identical twins have identical personalities?

It is important to remind ourselves that the claims of behavioral geneticists are not accepted by everyone. Most of us accept that genetics influence our personality. We also know, however, that experience can greatly affect who we become. We are not robots. Behavioral genetics does not offer a system to explain how experience shapes our lives.

In The Nurture Assumption, Harris introduces us to such a system, which she calls "group socialization theory." It proposes that children learn how to behave by classifying themselves into groups that exist among their peers. She contends that learning is context specific. Parents and family make up only one setting in which children learn to act. It is among their peers that children develop the personalities they eventually exhibit as adults.

If we can put our present views on the subject aside, The Nature Assumption provides an unexpected and fascinating framework for viewing the origin of personality. The arguments in the book are clearly stated and the tone is honest and appealing, although some readers may not appreciate the juxtaposition of personal anecdotes and scientific findings. For instance, Harris readily admits that raising her two daughters, one adopted, has contributed to her opinions.

The Nurture Assumption is not a scientific treatise intended to prove group socialization theory. Instead, it appeals to our common sense. Personal bias is inevitable when developing scientific theories, and Harris's straightforward admission of her own bias is refreshing. Proving a scientific theory - by rigorous testing - is what takes the bias out of science.

The question for us, then, is whether group socialization theory deserves our attention as a way to explain the nongenetic components of our personality. Certainly we can identify examples of what we might call group socialization.

Teenagers often display attitudes, fashions, and even criminal tendencies that are distinct from those of their parents. These views and behaviors appear to arise from a group mentality. Language also appears to arise at the level of one's peers. Children of immigrants learn to use the language of their peers, not that of their parents. Furthermore, children have a strong tendency, perhaps even stronger than that shown by adults, to see themselves as part of a group. Is this "grouping tendency" an all-important force that shapes our personality? Harris believes so. She also believes that our conscious mind is not aware of its importance and that our sense of group is separate in our minds from our sense of personal relationships. In her scheme, one-on-one relationships are prominent in the conscious mind but limited in their long-term effects. Our sense of group, on the other hand, is limited in our conscious mind but prominent in its long-term effects.

A serious problem with the book is that it does not restrict its claims. Group socialization is proposed to explain teen smoking, language acquisition, the differences between black and white culture, the ineffectiveness of crime deterrents, Yanomamo men tying their foreskins to strings, and, of course, personality. Does socialization within our group determine whether we smoke or not, or does it affect whether we're outgoing or nervous? How does our status within a peer group lead to a different personality? Harris does not provide us with explicit rules for the effects of group socialization.

The basis of the controversy this book has generated - the suggestion that parents have limited influence over their children - comes from the conclusions of behavioral geneticists. They tell us that inheritance accounts for all of the similarity between siblings and that parental style, which should be similar between siblings, has negligible effects. Harris's group socialization theory of personality development explains these conclusions by proposing that our personalities actually arise outside of the home environment, rather than from the intimacies of child-parent relationships as we have been led to believe.

The validity of the group socialization theory must come from its ability to predict human behavior. Will Harris's model lead to useful, testable predictions? For now, it is enough to enjoy the curiosity, speculation, and controversy that have followed the publication of the book.