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The Psychology Place, August 1997.

1997 Peregrine Publishers, Inc. All Rights Reserved

Challenging the Nurture Assumption
by Judith Rich Harris

Introduction, by Dave Myers, Hope College

Judith Rich Harris recants. Based on accumulating evidence, Harris no longer believes much of what she has taught students through her developmental psychology textbooks. What she once believed--also what most of us teach and what those ahead of us in the supermarket line believe-- is that parental nurture shapes children. What she now believes, for reasons she explains, is that genetic and peer influences trump parental nurture.

In a recent Psychological Review article and in her lucid forthcoming book, The Nurture Assumption (Free Press), Harris asks, "Do parents have any important long-term effects on the development of their child's personality?" After examining the evidence, she concludes "The answer is no." If we left a group of children with their same schools, neighborhoods, and peers, but switched the parents around, they would, she says, "develop into the same sort of adults."

If Harris is right, much else in the popular psychology of our age is dead wrong. Is she right? Attachment researchers, socialization theorists, authoritative child-rearing proponents, Freudians, co-dependency therapists, and those who worry about toxic parenting, father absence, and parental neglect, what say you? Are we teaching misinformation about the power of parental nurture? In a spirit of intellectual community and mutual support--Harris's book has not yet gone to press--feel free to join the dialogue (mostly with one another, but also perhaps with our guest speaker, who may from time to time join the conversation to answer a questions or respond to comments).


When he was seven and a half years old, a boy I will call Joseph moved with his parents from Poland to rural Missouri. He spoke not a word of English when he arrived in this country. Only a year later, according to the psycholinguists who studied Joseph's progress, he was a "sophisticated speaker of English" and had only a slight accent. A few years later they checked on him again and now his speech was indistinguishable from that of his American-born classmates (Winitz, Gillespie, & Starcev, 1995).

English was not the language his parents taught him, but English has become Joseph's "native language" -- the language he thinks in and dreams in. If he is typical of immigrant children, his Polish will never progress beyond the seven-and-a-half-year level; he may even (if he has no Polish friends) forget it entirely.

This is an important clue that developmental psychologists have too long ignored: an aspect of cultural knowledge and social behavior that is acquired in childhood, and that becomes a permanent part of the behavioral repertoire, cannot be predicted on the basis of parental input. Yes, Joseph learned his *first* language from his parents. But the language he will take with him to adulthood is the language of his peers.

Dave Myers' introduction revealed the shocking truth about my theory of development: I don't believe that parents have any important long-term effects on their children's psychological characteristics. I believe that all resemblances between parents and children are genetic. Parents give their children their genes; that's enough of a contribution. If they also had the power to shape their children's characteristics through environmental means, the children would be too much like little clones -- not at all what evolution was after when it filled our skulls with RAM and skimped on the ROM. Your children "come through you but not from you," said the poet-philosopher Khalil Gibran. "You may give them your love but not your thoughts. . . . For life goes not backward nor tarries with yesterday." Parents are yesterday; peers are tomorrow.

The greatest challenge for me is to explain why everyone -- in and out of psychology -- is so certain that parents do have important and lasting effects on their children. I call this certainty *the nurture assumption* (Harris, in preparation): it is the assumption that the formative aspects of the child's environment are the home and the parents. It is a myth of our culture and it is relatively new, dating only from the early part of this century. In other times and other places, people have not had the idea that the way they treat their children could determine what kind of adults they will turn into. The nurture assumption has turned child-rearing into an anxiety-producing job: if anything goes wrong with your kid, it's *your* fault.

Assumptions bias perceptions so that ambiguous evidence is interpreted as evidence in favor of the assumption. There is plenty of ambiguous evidence around -- developmental psychology journals are full of it. Almost every study of parental influence on children lacks a control for genetic effects, so there is no way of telling whether the resemblances seen between parent and child -- in competence, or helpfulness, or aggressiveness -- are transmitted genetically or environmentally. Researchers simply assume that some of the effects they see must be environmental. Similarly, there is no way of telling whether the correlations noted between parents' behavior and children's behavior are due to the parent's effect on the child or the child's effect on the parent: researchers simply assume that some of the effects must be parent-to-child.

Genetic effects and child-to-parent effects are not the whole story, however. Developmentalists ignore the fact that acquired behavior is highly dependent on context. Joseph speaks Polish when he is at home with his parents, and anyone who observes him at home (or with his parents) would see no reason to doubt the efficacy of parental influence. But Joseph abandons his Polish when he slams the screen door behind him and goes out to join his peers. There is not the slightest hint of a Polish accent in the language he speaks at school.

That is why I like to use language as an example: because it is free of the complication of genetic influences. A study in a development journal looked at children's obnoxious behavior (behavior that was bossy, obstructive, or aggressive) with their parents and their peers and found a correlation of .19 between them (Dishion et al., 1994). This is a surprisingly low correlation but it isn't zero -- in fact, it is statistically significant. The explanation is that obnoxiousness is partly genetic, and the genetic component of behavior travels between contexts -- our genes go with us wherever we go. But whether a child speaks Polish or English is entirely environmental, and in this case there is no carryover at all from inside the home to the world outside.

It is their experiences outside the parental home that modify children's personalities in ways they will carry with them to adulthood. Because humans are adapted by evolution to live in groups, I believe we must turn to sociological descriptions of group behavior to find the source of these influences (Harris, 1995). When people identify with a group they take on the group's norms of behavior. Children in modern societies have a ready-made group to identify with: their classmates. During the elementary school years, children learn to tailor their behavior to that of their same-sex peers. Differences between the sexes are sharpened by group contrast effects. And within groups, differences in social status and typecasting by their peers causes children to carve out distinct personalities for themselves -- personalities that may be quite at odds with what they're like when they're at home.

What happens to the personality that developed in the parental home? No, it doesn't wither away, though most of us wish it would. It comes back to haunt us every time we go home for the holidays. Look at the Thanksgiving table and you will see grownup offspring -- successful and dignified people in the world outside -- whining and bickering again, just the way they did when they were kids.


Dishion, T. J., Duncan, T. E., Eddy, J. M., Fagot, B. I., & Fetrow, R. (1994). The world of parents and peers: Coercive exchanges and children's social adaptation. Social Development, 3, 255-268.

Harris, J. R. (1995). Where is the child's environment? A group socialization theory of development. Psychological Review, 102, 458-489.

Harris, J. R. (in preparation). The nurture assumption. New York: The Free Press.

Winitz, H., Gillespie, B., & Starcev, J. (1995). The development of English speech patterns of a 7-year-old Polish-speaking child. Journal of Psycholinguistic Research, 24, 117-143.

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