HOME / dialogues: E-mail debates of newsworthy topics.

The Nature of Nurture: Parents or Peers?

dialogues:
entries

1 2 3 4 5 6

From: Judith Harris
To: Jerome KaganPosted Wednesday, Nov. 4, 1998, at 3:30 AM ET

Dear Jerry,

RSS

Let me begin with your assertion that I reviewed the literature selectively on the basis of my a priori bias.
Five years ago, my bias was the same as yours: I too was a believer in the nurture assumption. Up to that point I had focused on the literature of developmental psychology. The change in my thinking came after I read more widely in psychology and anthropology, in preparation for writing another textbook. It gave me a bird's-eye view of the field. Sometimes things can be seen from a middle distance that aren't visible from close up. I've noticed that psychologists who are not focused on a single area but who are able to see the bigger picture--writers of introductory textbooks, for instance--tend to be more receptive to my ideas.
Yes, there are behavioral differences between Mexican children and New England children. No, I wasn't going to claim that they are due to heredity. But surely you're not implying that you would object to such a claim, in view of the fact that you've attributed the behavioral differences between Chinese babies and Irish babies to differences in heredity!
You're way ahead of most developmentalists, Jerry, in your willingness to admit that genes play a role in how children behave. But even developmentalists who are willing to admit it are strangely reluctant to admit that, since children inherit their genes from their parents, genes can produce resemblances between children and their parents.
That study you mentioned from the August 1998 issue of Child Development? There are hundreds like it. The method provides no way of controlling for the effects of heredity. When researchers do use the appropriate controls, heredity is always found to make a contribution. Therefore it is scientifically indefensible to go on doing research that provides no way of controlling for these effects. The study also provided no way of separating the effects of the parents' child-rearing style on the child from the effects of the child on the parents' child-rearing style, even though we know that the parents' behavior is partly a response to the child's behavior.
Nevertheless, this study did produce an interesting result: No differences were found between children who entered day care in early infancy and those who spent their first three years at home. Which brings me to what you said about correlations. I never claimed that correlations are "no basis for inferring anything important": I said they are ambiguous. If you find that two things tend to go together, you don't know what caused that correlation. You need additional information to explain it. But if you discover that two things are not correlated, you've learned something. If the amount of time children are cared for by people other than their parents is unrelated to the children's behavior and adjustment, that tells us something important, doesn't it? Doesn't it tell us that a lot of the advice being given to parents is hogwash?
The differences between adopted children reared in middle-class homes and those reared in working-class homes do show up in studies that control for heredity (see Capron and Duyme in Nature, Aug. 17, 1989). But you were going well beyond the data when you said, "The differences in cognitive skills had to be due to the family practices and not to genes." There is a third alternative you haven't considered: They could be cultural differences, like the difference between the Mexican kids and the ones from New England.
When children reared by middle-class parents live in middle-class neighborhoods and go to middle-class schools--which is almost always the case--you can't tell whether the effect on their cognitive skills is due to the home environment or to the environment outside the home. The problem is that the two environments match. You have to look at cases where they don't match to see what's really going on. You have to look at cases where the parents' culture differs from that of most of the other families in the neighborhood.
I describe many such cases in my book. The children of immigrants: They adopt the language and culture of their peers. The hearing children of deaf parents: They adopt the language and social behavior of the hearing culture, not those of the deaf culture. Kids from fatherless, low-income families who live in middle-class neighborhoods are as unaggressive as their middle-class peers, whereas kids from similar families living in low-income neighborhoods are highly aggressive (see Child Development, April 1995). When there is a cultural discrepancy between the home and the neighborhood, the child starts out with the home culture and ends up with the neighborhood culture. But in most cases there is no discrepancy between them, and no need to change. Almost all your data come from those uninformative cases.
The idea that parents have important and lasting effects on their children--is it universal? No. See Chapter 5 of my book. But even if it were universal, would that make it true? Didn't everyone used to believe that the Earth was flat?
One of our problems is that you seem to think of the study of children as art or literature, and I think of it as a science. You talk about what people say in their autobiographies and what they tell pollsters who ask, "Do parents matter?" I happen not to believe that we can answer scientific questions by means of public opinion polls.

Judy