The Nurture Assumption

The Nurture Assumption

review of a book by Judith Rich Harris

In a very interesting book, Ms. Harris presents considerable psychological and anthropological data to reexamine the “Nurture Assumption,” or the belief that nurturing your children will lead to happy well-adjusted children, and that if your children grow up otherwise then logically you didn’t nurture them. Her explanations are clear and her ideas well presented.

However, Ms. Harris makes some of the same mistakes as the developmental psychologists she criticizes–mistaking correlation for causality, interpreting questionable data according to preconceived “truths,” and overestimating the significance of some studies. Despite this, many of her ideas bear much closer examination. She rightly points out that psychology as a whole has given less attention to these three areas; 1)the powerful role of peers, 2)the unappreciated role of heredity, and 3)alternate reasoning to explain many of the “facts” that underlie the Nurture Assumption. It’s been almost a year since I read her book, and I have to admit that although I disagree with some of her conclusions, I have found many of her ideas and thoughtfully reasoned points to be useful in my personal and professional life. A brief review of her ideas would go as follows.

The Powerful Role of Peers in Shaping Children’s and Teen’s Behavior

Ms. Harris discusses the highly influential role that peer and social groups play in shaping behaviors, opinions, goals, values, and language. She examines anthropological data to understand why social groups are so important to us, and why changing groups affects us as it does.

Ms. Harris highlights how the “rebellious teen” is produced by the same factors that produce adolescence in general. Because teens do not fall in the “children” group or in the “adult” group, they struggle to define their own group that is maximally different from the other two, but as internally consistent as possible. It explains why teens do not carry lunch boxes and do smoke to the annoyance of their parents. Doing so helps them to form an easily identifiable group, support each other, and resist efforts by “outsiders” to change them. Drawing upon scientific studies, Ms. Harris explains what every parent knows to be true–sometimes your children do the exact opposite of what you say just to be contrary. They do not do it to make you angry, although this may be a fringe benefit. Rather, they do it to better define themselves as “teenagers.”

In short, in this area, Ms. Harris gains one point over traditional psychology.

The Unappreciated Role of Heredity

While Ms. Harris criticizes traditional psychology for its “hindsight” theorizing–“she is this way because her mother was too strict” and “he is this way because his father was too lenient”–she also offers heredity as a similar multipurpose explanation for behavior. “She is this way because of her genes,” and “he is this way because of his genes.” For example, Ms. Harris offers is that there is no “divorce gene,” for example, but there could be genes that moderated traits such as agreeableness, impulsiveness, and social perception and participation. These traits would combine to make happily married, or not combine in others to produce unhappily divorced people. Thus, your three unsuccessful marriages might have very little to do with your parents’ behaviors, and more to do with the genes they gave you.

While this explanation is reasonable, there is no proof to support it. Any author would face this criticism, however. The fact is, we know that genetics play a large and important role in human development, but we simply don’t understand the nature of genes, environment, genetic and environmental interaction well enough to speculate on exactly how they interact to affect all people, much less any individual.

In short, in this area, traditional psychology and Ms. Harris reach a draw.

Alternate Reasoning

Finally, Ms. Harris offers considerable discussion, drawing from multiple areas of developmental, clinical, social, and anthropological fields to discuss alternate reasons to explain the correlational findings that underlie much of the “Nurture Assumption” research. Ms. Harris offers the observation that “good” parents seem to have “good” kids. The Nurture Assumption argues that the first must produce the second. Ms. Harris offers instead that “good” parents may appear to be so due to their genetic endowment. They may have genes to be more “easy-going” and even tempered. Passing these genes on to their children can lead to similar “good” children. Further, children who are easier to care for make their parents look “good.” “Bad” parents may have genes to be more tense and less comfortable adapting to change. Passing these genes on to their children can lead to similar “bad” children. Further, these children may be more difficult to care for and in return make their parents look “bad.”

In short, in this area for the same reasons noted above, Ms. Harris and traditional psychology reach a draw. We can’t prove her ideas or traditional ideas, but her explanations are at least as reasonable as the traditional ones offered.

Other Problems

Ms. Harris notes that her largest problem with her book since its publication is that of people quoting her ideas and statements out of context, and making judgments of the book without having read it.

Some would take Ms. Harris’ ideas to mean that since parents have no control over their children and what kind of people they will be, parents are not responsible at all for their children. Ms. Harris does quite clearly say that mistreating your children is harmful to them. Further, she does not argue that parents should “just throw in the towel” and give up efforts to teach and discipline their children. She argues that all a parent’s efforts to control, teach, and nurture their children have an impact at home. What she argues, however, is that the impact of these parenting efforts is limited to the home. That’s where it ends. How you teach your children to act at home will not significantly impact how they act at school, the mall, or their friend’s homes. In other words, you should not feel bad if your children engage in petty thievery and smoke at school. The fact that you did not teach them to act this way at home has nothing to do with their behavior. Treating your children well, teaching them to share and respect others in the home, and establishing family rules for behavior certainly makes family life more pleasant, and helps you to build better relationships with your children that will last into adulthood. In other words, many of the things that “good” parents have been doing, they should continue to do. However, Ms. Harris’ point is that it is unreasonable to expect that these efforts reach beyond the home environment.

However, this realization should not dishearten parents. What parents can do to be more helpful to their children and to improve their lot in life is to more carefully choose their environments. Living in “good” neighborhoods, going to “good” schools, and seeing that your children have “good” peers will help. However, Ms. Harris cautions that these factors will only help to a point. Some children are simply more likeable than others, and other children respond differently to them. You can’t change this any more than you can change your children’s genes or your own similar tendency to like some people more than others. Ms. Harris offers as well that if you feel guilty that you like one of your children more than another, you should not. One of your children may simply be more likeable than the others.

These points aside, I still do have some criticisms of the book. First, I think Ms. Harris oversimplifies the parent child relationship and the meaning of nurturance; second, I think that she relies too heavily upon questionable anthropological data; third, I think she underestimates some of the basic assumptions of the developmental research.

Oversimplified Issues
Ms. Harris assumes that for the “Nurture Assumption” to be true that children must learn from their parents only by modeling. She points out that children watch their parents leave the house every morning for work, boss others around, and drive cars. They do not try to do the same thing, however, and this refutes, in her eyes, the role that parents play as teachers. She explains that children learn how to be children by watching other children. Using her arguments about modeling, I would have had to see other children begin working on their homework as soon as they got home from school before I would have done it for the first 10 years of my schooling.

In short, I think that Ms. Harris oversimplifies the ways and the things that parents teach their children. Teaching your child how to think, weigh alternatives, and consider the results may still affect them outside of the home. Just as much of the schoolwork I completed at home helped me in school (outside of the home), much of the ideas about interacting with friends and romantic partners, setting and working toward goals, and saving and spending money that I learned at home affected my life after I moved out of my parents’ home.

Ms. Harris also oversimplifies the “Nurture Assumption” to mean that it is only how parents respond to the child that is at issue. Parents, grandparents, aunts and uncles, ministers, scout leaders, and teachers all affect children even though they are not their peers. The nurturance, support, challenge, and modeling that these adults provide also affect children’s expectations of the adult world, of adult problems, and adult solutions.

Ms. Harris does make a valid point that assuming that all your relationships are based solely on your relationship with your parents is going too far. However, most psychologists I know would not have made that extreme of an argument. Rather, most psychologists I know point out that your relationship with your parents is likely to be the first, longest, and most time consuming relationship that you have in your life. The power of that relationship can be seen as stemming from those factors. Likewise, a 20 year relationship with a mentor, minister, friend, or partner can have significant effects as well.

In short, I think Ms. Harris oversimplifies the meaning of nurturance and the impact of more versus less nurturing relationships.

The Role of Anthropological Data
Ms. Harris draws many of her conclusions about the role of peers and parents in children’s lives by looking to other cultures. On the one hand, there is something to be said for this line of argument. Studies of early Native American parenting practices, parents in South American villages, and children from South African tribes allow one to get to a “distilled” or extremely basic idea about what all human parents do and how they do it. On the other hand, this line of reasoning has a major drawback. Anyone who uses this kind of data must question its applicability to their specific, very different culture. If Ms. Harris could show beyond all doubt that parents in one culture do not “nurture” their children and that their children “turn out” fine, does that logically mean that our efforts to “nurture” our children make no difference? If parents in a South American village allow their children to eat whatever food they please, and their children grow up healthy, does that mean that we could do the same here in America and have healthy children? Questions such as “Do both groups of children have access to the same foods and medical care?” and “Do both groups of children follow the same eating habits?” make comparisons between the two groups very difficult.

Another problem in this argument is that the comparison is between what one group of parents doesn’t do and the results, and what another group of parents do and the results. If one group of parents do not monitor their children’s eating habits, what does that tell us about parents who do monitor their children’s eating habits? The answer is far from clear.

Further, many of the parents in the other cultures do not face the decisions that today’s American parents face. Issues such as encouraging your teens to stay out of gangs, avoid drug use, vote democratic or republican, go to college, or avoid pornography on the internet have little impact in other areas of the world. Their parenting practices, while applicable to their world, may not be applicable to ours.

Several times Ms. Harris explains studies in detail, and draws conclusions about these results for the reader. Her explanations are clear and concise, and many of her conclusions seem reasonable. However, at other times she simply states that “all the research” agrees with a given study, only briefly summarizes a piece of research, and gives very limited footnoting and explanation for the link between the results and her own conclusions.

Assumptions of Developmental Research
Finally, Ms. Harris approaches much of the developmental research by pointing out that the “Nurturance Assumption” is held before the research is conducted, and its implications are used to interpret the research results. This is likely true. However, she goes further than this.

Ms. Harris gives examples of research that studied identical twins that were raised by adoptive parents. In children born to noncriminal parents and raised by adoptive parents, 20% became criminals. This held true even regardless of whether the adoptive parents were criminals. However, she notes that of children born to criminal parents, a higher percentage grew up to be criminals. This would seem to support that the genes we received from our parents may be more important in determining our life outcome than the nurturance efforts of adoptive parents. She goes further and notes that where one twin became a criminal, there was a 45% chance that the other twin would too. This would also seem to support that genetics play a large role in adult behavior.

However, she does not explain why 55% of research participants with a criminal parent and a criminal identical twin did not become criminals. The hereditary factors were stacked against them so to speak, yet they resisted. Ms. Harris does say late in the book that she hoped that reason could outweigh hereditary factors in some cases, but she does not say where or how reason would do so, or define reason. I like to think the same, however, and I think that reasoning skills come from the kinds of “nurturance” a child receives from parents and other adults in his or her life. In therapy with parents, I point out that teaching your children how to think, take other peoples’ views and needs into consideration, and better know their own strengths and weaknesses is much more important than making the “you are bad” and “what you did is bad” distinction that some expect me to make.

The other problem with her reading of childhood nurturance and adult adjustment is that the lack of an apparent connection between them does not indicate that one did not exist. For example, childhood vaccinations do not lead to adult health. Adult behaviors such as drinking and eating too much, poor exercise, and stressful lives can impact health. However, childhood vaccinations might prevent certain adult illness, and that is all we expect them to do.

In the same way, nurturing your child may not be strongly correlated with adult adjustment, since many factors affect this final outcome, not the least of which is all the decisions your grown children will make when they leave home. However, nurturing your child may still be a preventative factor for poor adjustment, just like vaccinations can prevent some illnesses. What if love and nurturance don’t “make” children grow up to be happy and well adjusted adults, but only protect children from some adult emotional and psychological problems? To really know, we would have to compare the adult adjustment of children who received nurturance and children who received non-nurturing but non abusive treatment. Defining that, of course, is quite difficult and some would argue that such treatment would only come from strangers who had no emotional investment in the child, and thus they were neglectful.

Psychologists as Experts

Ms. Harris also addresses the role of psychologists and other experts in the work of parenting. While she, and others, have pointed out the inadequacies of psychological and other advice on child rearing over the years, I think she misunderstands the role many psychologists adopt.

I don’t see my role as a psychologist as being that of an expert who tells parents what they should and should not do. Rather, I am a consultant that offers ways to extend and improve upon good parenting. For example, advanced irrigation techniques in farming are not the result of changes in the earth, sun, or weather; nor are they brilliant ideas that “Mother Nature” never thought of. Rather, they are extensions of “Mother Nature’s” principles applied at a new level.

Let’s be more specific. Ms. Harris says that smart parents read to their children, and their children grow up smart. Thus, some conclude, reading to your children makes them smart. She offers instead that smart people have smart genes which they pass to their children, and that’s what makes them smart; the reading is irrelevant. But take this further. Parents who are great swimmers may pass on genes for great swimming to their children. But, if they never take their child to a pool, lake, or ocean, the child is unlikely to learn to swim and will never be a great swimmer regardless of her genes.

I think Ms. Harris is correct in pointing out that even with great genes, your daughter may learn to swim, but may never be a great swimmer unless her friends value swimming or at least don’t devalue her for her swimming. Likewise, if you want her to swim, sending your daughter to a school with a swim team, and making sure she has the opportunity to associate with other children who value perseverance, athletics, internal motivation, and swimming are more likely to be effective than pressuring and ordering her to swim.

Ms. Harris, curiously, goes on to say late in the book, “that some behaviors, especially those at home that peers do not see, are immune to peer effects.” These behaviors include cultural cooking techniques, family games, and other cultural and social behaviors that persist into adulthood. She does not explain why cultural behaviors from home would persist, but values about right and wrong, ethics to live by, and morals about what people do and do not do would not persist.

I think experts play an important role here. We do not necessarily tell parents how to be “good” parents. Rather, we can identify the key elements of what “good” parents have discovered over the years and continued doing, and then help parents apply that knowledge more effectively, and at a new level, to deal with the new problems those parents face. Applying Ms. Harris’ views, some parents learn more from other parents, their peers, than experts. Likewise, we can not “make” “good” parents from “bad” parents; some parents lack the basic characteristics to be “good” parents. Further, some of what looks like it would lead to good parenting and good adult adjustment, in fact, doesn’t.


In the end, I think Ms. Harris has made good points, and as much as possible made them in common sense and easy to understand ways. She is right in that peers and genetics play a large role in how children develop, and parents are not always responsible for the behavior of their teens and grown children. Likewise, “good” parenting often means accepting the role of the world outside the home in more realistic terms. Further, parents should not feel guilty for liking one child over another, since some children are more likeable than others. These are not profound statements and realizations, but ones that psychologists do often ignore.

However, while Ms. Harris may have shaken “the Nurturance Assumption” in the classic sense, she has not really toppled any psychological theories or shaken the “nurturance assumption” most of us make. If nurturance in nothing more than hugging and kissing a child, then yes, she has clearly shown that it will not reliably produce happy well adjusted adults. However, if nurturance is assumed to include more behaviors, coming from more than just one’s parents, that serve more as a preventative agent for adult problems than a guarantee of adult happiness and adjustment, then the assumption most of us make remains.

If you provide the kinds of limits and love that teach your children about themselves and the world, help them build relationships, and provide emotional stability, considerable psychological research show that you “inoculate” your child against many of the problems adults can face, and give them a chance to find their own happiness and adjustment. You can not, however, claim sole credit or discredit for their happiness.


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