How Much Do Parents Matter? Reading and Misreading Behavior Genetics

Bing Nursery School


Professor Eleanor Maccoby, Bing Distinguished Lecture Series

By Christine VanDeVelde

How much do parents matter? How powerfully are children influenced by their parents? What role do genetics play? These compelling questions were the subject of a presentation by Professor Eleanor E. Maccoby at the 2001 Bing Nursery School Distinguished Lecture, held on May 31st at Stanford University.

"I want to start out," said Dr. Maccoby, "by saying of course parents matter in the way children live their daily lives, and in what happens to them. You may ask why would anybody doubt it." And yet they do. The controversy surrounding this subject was ignited, though not for the first time, when, three years ago, New Jersey psychologist Judith Harris published The Nurture Assumption: Why Children Turn Out the Way They Do, Parents Matter Less Than You Think and Peers Matter More.

The media, of course, went to town with Harris' message. According to Maccoby, one of the reasons that Harris' book attracted so much attention was that it let parents off the hook. It said, "You don't need to feel so guilty if your children give you difficulty and if they aren't developing exactly as you would like--it's all because of their genes, basically." There was, of course, outrage from many leading researchers on parent-child relationships and their effects, but there was also some support for Harris' work from several prominent psychologists.

"This is really not as bad a book as some of my friends believe it to be," says Maccoby. "I like its lively style and it's really quite well written." For example, Maccoby quotes, "Socialization researchers start out with the preconception, the idea, that there are good child-rearing styles and bad child-rearing styles, and that parents who use good ones will have better children than those who use bad ones. Just as we all know the rules for a healthy lifestyle, we know all the rules for good child-rearing. Give children plenty of love and approval, set limits, enforce them firmly but fairly, don't use physical punishment or make belittling remarks, be consistent and so on. We also have a pretty clear idea of what we're looking for in a child. A good child is cheerful and cooperative, reasonably obedient but not to the point of being a robot, is neither too reckless nor too timid, does well in school, has lots of friends, and doesn't hit people without good cause." "It's clever," notes Maccoby.

Harris' message is that the effects of parenting have been over-emphasized. She points out that in early studies of socialization when connections have been found between the way parents deal with their children and how the children turn out, they are often quite weak. But, what she omitted, says Maccoby, is that in up-to-date research with better measurement and better ways of choosing what to measure, stronger connections between what parents are doing and what childrenare like continue to be found. The connections between what parents do now and what children are like now are quite strong, in fact. It is more difficult to predict what a child will be like three or four years from now based on what parents do now.

Harris also argues that when you do find a connection, it says nothing about whether the connection has arisen through parental influence on the child--or the reverse. Harris says there may not be influence flowing in either direction. It may just be that stable and well-adjusted and happy parents are that way because of their genes, and they've passed those genes on to the children who, therefore, are stable, happy and well-adjusted, so this doesn't mean that the parents are influencing their children. And, of course, the reverse is possible, as well. That is, an obstreperous uncooperative child can push parents into being coercive or punitive; while, with a child with an easier disposition, parents are able to be kinder and more responsive.

So, is there a way of finding out what role children's genetic endowment plays? Well, yes, Harris says. She relies upon studies of twins and adopted children and the widespread belief that if genes are important, then environmental influences must be unimportant. Maccoby stresses that molecular geneticists do not take this view. Genes and environment, they say, are interwoven at every step of the way and genes often need environmental or experiential triggers to turn them on. But the behavior geneticists make genetic and environmental influences seem as though they are either-or alternatives. Their studies of twins and adopted children find that identical twins are more similar than fraternal twins, and they say that points to genetic factors, because, after all, both sets of twins are growing up in the same family. If anything makes identical twins similar, it must be their shared genes. They also report that adopted children are more similar to their biological parents than they are to their adoptive parents.

On the basis of these kinds of studies, Harris and others with her point of view claim, first, that genetic factors do make a substantial contribution to individual differences among children in many aspects of development. Secondly, they maintain that, among the environmental factors, it is the ones that are not shared by children in the same family that have the most influence on how children turn out. Things such as the parents' cultural level, their education, their income, the neighborhood where they live, their ethnic or religious background, the amount of harmony or conflict between the parents--these are all parts of an environment that children in the family share, and these things, Harris argues, cannot be making much difference in the way children turn out.

"Now, let me say immediately that behavior geneticists have firmly established that there are genetic factors influencing how children turn out," interjects Maccoby. While it is true that estimates of heritability do vary, depending on the population group that was studied and how the trait was measured, it is now widely accepted that children's genetic endowment is an important contributor to their development. Maccoby considers this to be well-established.

But the second claim, that aspects of the environment shared by children growing up in the same household don't affect their outcomes, is much more controversial. "Indeed, I think it is wrong," says Maccoby, "even though it's true that siblings growing up together are often quite different from one another." The idea that a shared environment doesn't affect the children growing up in it flies in the face of much of the evidence about environmental risk factors. Growing up in poverty, parental conflict or abuse, dangerous neighborhoods, disorganized family life--these things all have predictive power for poorer adjustment and lower achievement for children in such families. But, if parents, on the other hand provide appropriate support and structure, set limits and monitor a child's activity and compliance, and see to it that they do comply with the limits that are set and at the same time are warm and responsive--these things increase the chances of a child becoming a competent teenager and adult.

So, why do behavior geneticists continue to report no absolute effects of a shared family environment? One reason, says Maccoby, is that there are influences within the family that may not affect all the children in the same way. The way that behavior geneticists have interpreted their data has meant that they have seriously underestimated shared environment effects, according to Maccoby, who cites numerous studies that show that environmental factors, such as income or parents' education, in fact have powerful effects. These studies show that outcomes depend not only on the genetic qualities that children bring with them into an adoptive home, but, also on the kind of environment that is provided in the adoptive home, and that these two things join together.

Additionally, other studies document the fact that children react differently to the same kind of treatment from a parent. One study contrasted children who are bold and adventurous with those who are timid and shy. It was found that the bold and adventurous children benefited more from firm control, that the parent needed to be responsive but also willing to confront the child and stop unwanted behavior. The timid and shy children benefited less from that kind of treatment and more from gentle treatment. So those parents with a shy or timid child will moderate what they do, and not be so confrontational with the child. "The fact that parents need to adapt their child rearing to individual children's temperaments doesn't mean that parenting is making the siblings alike," says Maccoby. "In fact, it may be making them different, but obviously what they're doing is not ineffective. They are having an influence."

When behavior geneticists point out how parents don't treat all their children the same, they are fond of saying that these are "evocative effects." That is, the parents' behavior is being evoked by the child's action, and the child's action is driven by the child's genes--so a beautiful, naturally sweet-tempered child elicits gentle, positive parenting and unattractive children with difficult temperaments are more likely to be ignored or reacted to in negative, irritable ways. So, once again, the behavior geneticists' reasoning is that it's the child's genes that are driving the parental behavior and that any correspondence between what parents do and how children turn out can be safely assigned to the child's genetics.

"Now, do children with different temperaments influence how their parents treat them? Of course they do. Does this mean that the correlation between what parents do and how children turn out reflects mainly the child's genetics? Of course not. In any long-standing relationship, each partner must influence the other. To suggest that the parent-child relationship is a one-way street with influence flowing only from the child to the parent is, I think, absurd. Reciprocity is the name of the game between parents and children," says Maccoby.

It's not an easy thing to determine just what effect parents are having or how strong or lasting such effects are, Maccoby admits. Experiments can seldom be done assigning families to a treatment or assigning children to a certain kind of parenting. But the evidence that is beginning to accumulate fits in very well with the overall research picture that is forming--that both genetics and parenting matter. In summary, Maccoby believes that there is solid science supporting the view that the ways parents interact with their children does have an effect on them, though, of course, parents are not the only important source of influence on children.

"But why should we care about all of this?" she asks. Because in magnifying and misinterpreting the work of Harris and her followers, the media has created a situation with important political implications. "If one does believe that genetics have a strong effect on children's outcomes, and that conditions such as poverty, parental conflict, coercive or abusive parenting, dangerous neighborhoods--all the things that behavior geneticists call shared environmental factors--if one believes that these are unimportant for children's welfare, then there's very little point in trying to intervene to change them," says Maccoby. This thinking leads to questioning the existence of any intervention programs--like Head Start, for example--that are designed to improve parenting or give support to parents in general. "There are large numbers of families in this country in which parents are trying to raise children under highly stressful conditions," says Maccoby, cheerfully noting her liberal bias. "They need all the help they can get. We know how to help them in ways that will foster good adjustment and improved achievement for their children. I think we as a society should do these things."