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The Nurture Assumption

by Judith Rich Harris


Have you heard about the book that says parents do not matter? The Nurture Assumption is not that book, but Judith Rich Harris does argue that parental actions have almost no direct influence on adult personality unless a parent physically damages the brain. Harris blasts fretful, immersion parenting. Humans grow. Except for catastrophes, the everyday things parents do when children are three have little influence on thirty-year-olds.


Harris argues inherited traits and non-parental social groups form personality. Her mildly vague concept of personality has some overlap with moral character, but should not be confused with character. Her definition of personality covers style, popularity, criminality, intelligence, mannerisms, social adroitness, and psychological health--including impulsiveness, perseverance, and choice of response to boredom. A researcher working to eliminate guinea worm could have the same score on a personality test as a salesperson hawking herbal remedies, yet something very, very different between these two individuals exists, much more important than their tendencies to giggle. The difference is character.


Harris splendidly argues that heredity accounts for about half of personality variation and environment the other half. Twin studies suggest none of the environmental half results from everyday parental practices. Identical twins in separate homes have personalities as similar as twins raised in the same home.


She writes that researchers mean both direct and indirect genetic variation when they say heredity. If, for example, I were ugly, that ugliness influences my environment because humans treat the unattractive with unmitigated kindness, which might influence me to respond in ways that change my personality. This influence is an indirect effect.


The effects similar heredity can be drastic. Suppose someone has genes that cause her to join the worst crowd. In one culture the worst crowd murders and rapes. In another culture the worst crowd refuses to clean the bedroom.


In the home, a place where parents can influence children, parents and children mutually create child-rearing practices. The home environment is not merely a matter of parents imposing conditions. But once children are out of parental sight, parents have little influence on personality.


Harris champions the view that personality depends on social context. Humans follow group norms, especially young humans, often in the worst ways. Leaders of peer groups are among the most powerful moralizers. “Group socialization theory” is her phrase for it. As a result, moral adults should vigorously create and influence childrens' cultures. These childhood cultures minors should not be designed by 19-year-old men or CEOs whose only interest is profitability.


In the Harris system, beliefs often travel from individual adults to adult groups to children’s groups (especially peer leaders) and finally to the individual child. Joe Camel, for example, travels from an ad exec throughout an ad agency, to older teens, then to younger teens.


Joe Chemo travels from writer to magazine editor, to a handful of readers because parodies of major corporations are rare in mass media.


Children adapt to environments because children who always obey parents head for trouble. Flexibility is a gift. The interests of parents and children conflict. Mindless obedience equals child peril. Children must often learn to avoid parental actions, for example, playing with matches.


Considerable research suggests that peer, teacher, and community cultures of achievement strongly affect academic performance. Cultures emphasizing the belief that we can control our lives through our efforts, that we are responsible for what happens in this world.


Harris uses an elementary school teacher so popular years later adults, who were never her students, claimed to have been her students as an example of an adult who changed the ideals and actions of groups of young people. (Research psychologist Jean Twenge alleges elsewhere that anxiety levels of children aged nine to 17 in the 1980s and 1990s were higher than the levels of 1950s psychiatric patients. Weaknesses in social relationships and perceptions of risks of war, HIV, and environmental problems are potential causes.)


Harris leaves open the ideas that parents can:

·        Teach technical, educational, and philosophical skills.

·        Choose neighborhoods, peer groups, and larger environment while children are young. Parents should think about big picture influences on children, avoiding worry about damage from ordinary mistakes. If a parent joins a cult and moves to Rangoon, the new environment affects children.

·        Influence choices of careers and hobbies, politics and religions.

·        Form a family group with an us-against-the-world-mentality. Only strong, determined parents need apply.

·        Influence in home love, respect, happiness, and behavior.

·        Parents can influence the group norms that end up influencing their children.


The Nurture Assumption does not let parents off the hook. It changes the hook. If a 16-year-old has serious problems, what the parent does now may have little affect (parents should still try to help, of course), but major environmental decisions made while the child was young or spousal decisions made before the child was born affect much. Those who marry ex-convicts should not be surprised at the behavior of their children. Harris, however, does not emphasize prenatal care and injuries enough.


Also on the hook are other adults, especially those in powerful positions. They influence children, and they influence the groups that influence children. The details of how this should be done Harris leaves for someone else.


One point Harris should have made more explicitly: Variation due to heredity or environment is not modifiability. For example, most variation in hair color results from heredity, yet hair color is easily modified by the environment, that is, a dye rich environment. Individuals should not walk around with the fatalistic attitude that genetic variation gives the final word on obesity, substance abuse, and so on. Harris also makes some unhelpful appeals to the expertise and traditions of hunter-gatherers.


Harris trashes Frank Sulloway’s birth-order-matters book. Not merely a rhetorical trashing, Harris delivers a logical trashing. She destroys the idea of being born first, second, or whatever affecting adult personality.


When I first saw this book, I thought it would be like almost every other book on book-of-the-year lists: Overrated. I was wrong. Harris knows her stuff. Highly recommended.


J.T. Fournier, last updated July 26, 2009


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