In her seminal book ‘The Nurture Assumption: Why Children Turn Out the Way They Do’, psychologist Judith Harris argued that parents play less of a role than they think they do in shaping their children.

“The idea that we can make our children turn out any way we want is an illusion,” she wrote. “You can neither perfect them nor ruin them.” 

“Do Parents Matter?” asked the cover of Newsweek after the book was published in 1998. Yes, Ms. Harris said, parents do matter; a parent’s behaviour toward a child will affect how the child acts, at least in the parent’s presence, and it will help define what kind of relationship the two will have as the child grows up. 

But genes and peers play an even bigger role, she said.

Social psychologist Carol Tavris says the originality of The Nurture Assumption lay not in the studies Ms Harris cited, but in the way she has reconfigured them to explain findings that have puzzled psychologists for years.

First, researchers have been unable to find any child-rearing practice that predicts children’s personalities, achievements or problems outside the home. Parents don’t have a single child-rearing style anyway, because how they treat their children depends largely on what the children are like. They are more permissive with easy children and more punitive with defiant ones.

Second, even when parents do treat their children the same way, the children turn out differently. The majority of children of troubled and even abusive parents are resilient and do not suffer lasting psychological damage. Conversely, many children of the kindest and most nurturing parents succumb to drugs, mental illness or gangs.

… even when parents treat their children the same way, the children turn out differently

Third, there is no correlation – absolutely none at all – between the personality traits of adopted children and their adoptive parents or other children in the home, as there should be if ”home environment” had a strong influence.

Fourth, how children are raised – in day care or at home, with one parent or two, with gay parents or straight ones, with an employed mom or one who stays home – has little or no influence on children’s personalities.

Finally, what parents do with and for their children affects children mainly when they are with their parents. For instance, mothers influence their children’s play only while the children are playing with them; when the child is playing alone or with a playmate, it makes no difference what games were played with mom.