A new book by Judith Rich Harris, The Nurture Assumption: Why Children Turn Out the Way They Do, argues that peers have more influence than we think and parents have less. For the sake of discussion, we asked Jerome Kagan, a psychologist at Harvard University, to share his views about the importance of parents in their children's lives.

That parents exert a minor influence and peers a major influence on a child's development-the chief claim in The Nurture Assumption-ignores some important facts, ones that are inconsistent with this book's conclusions. Indeed, there is ample evidence that, for better or worse, parents do shape their children.

Consider, for example, that the best predictor of a child's verbal talent is the frequency with which the parents talk and read to the child. A verbally talented child is more likely to get better grades in school, and therefore is a little more likely to attend a better college. That, in turn, makes it more likely that in adulthood he or she will land a better job.

Moreover, a parent's education (whether they are, for example, a high school dropout or a college graduate) can predict how their child will fare in the world. Parental educational attainment, which is related to their child-rearing practices, predicts, among other things, the probability of aggressive behavior and the likelihood of psychiatric problems when these children become adults.