Before the Tiger Mother ever roared, author Judith Rich Harris stirred parents into a frenzy with a similarly controversial — if opposing and much more evidence-based — claim. In her 1998 book, The Nurture Assumption, Harris argued that when it comes to children’s success, parents don’t matter at all: the variance in children’s outcomes that we see is pretty much entirely accounted for by genes and peer influences, except, perhaps, in cases of extreme abuse. (More on Time.com: Behind the Viral Video: What’s the Deal with ‘Baby Yoga’?)
Saturday, in the Wall Street Journal, science writer Jonah Lehrer made a similar case, but only regarding rich parents, not poor ones — at least in terms of early child intelligence.
For her book, Harris reviewed massive amounts of data on parenting styles, and found that much of it was ridden with methodological flaws. In her review, there was little research to suggest that parenting made any huge difference in child personality. She noted that societal swings in parenting practices — from strict to permissive and back again — didn’t seem to change much the fundamental mix of personalities or intelligence that we see. But it’s not clear whether these findings are really due to a lack of effect, or an inability to measure it and disentangle all the variables.
Some research has now connected astonishing differences in children’s verbal intelligence, with their exposure to language at home. Most famously, Betty Hart and Todd Risley found that children from poor families entering preschool knew only half as many words as those raised by college educated professionals — and they demonstrated that this was because low-income kids heard roughly half as many unique words spoken to them at home. (More on Time.com:The ‘Tiger Mother’ Debate: Are Chinese Moms Really So Different?)
Now, based a new twin study that followed 750 identical and fraternal twins from age 10 months to 2 years, Lehrer argues that the influence of poor parents matters, but that of rich ones does not. The study found that 80% of the difference in kids’ intelligence by age 2 was attributable to home environment — but only among poor kids.
The opposite pattern appeared in 2-year-olds from wealthy households. For these kids, genetics primarily determined performance, accounting for nearly 50% of all variation in mental ability. (The scientists made this conclusion based on the fact that identical twins performed much more similarly than fraternal twins.) The home environment was a distant second. For parents, the correlation appears to be clear: As wealth increases, the choices of adults play a much smaller role in determining the mental ability of their children.
That idea, however, misses a few big things. For one, as Lehrer notes, the study did find that at age 10 months, parents were the biggest influence on children’s intelligence across all socioeconomic classes. Since later development builds on earlier experience, it’s not as though the first 10 months don’t count.
Secondly, choices about things like child care can matter tremendously. Although this is an extreme example, in our book Born For Love: Why Empathy Is Essential and Endangered, my co-author, child psychiatrist Dr. Bruce Perry, and I tell the story of a wealthy child who was parented by multiple sequential nannies. When the child seemed to become more attached to a nanny than to his mother — which was inevitable because the nanny spent the most time with the child in this family — that nanny was fired. The family went through 18 different nannies, subjecting the child over and over to the stress of abandonment, and the boy grew up to be a sex offender. Dr. Perry has also seen other cases of severe consequences of this kind of disrupted care-giving in wealthy children. (More on Time.com: The Daddy Bonus: Which Fathers Get Paid More at Work?)
Most parents don’t do anything nearly that harmful, of course — but research does find that child-care choices make a difference, and it’s not always the case that rich parents make wise ones. Having access to much better quality care helps, but spending time with your kids and knowing what’s appropriate for their development does too. After all, as Harris pointed out, even if kids are largely influenced by their peers, parents have a huge influence on who those peers will be, because they choose where their kids live and go to school.
Harris was correct to point out the flaws in the evidence that show that parenting is the main determinant of a child’s future. (I’d love to see her debate Tiger Mom!) And Lehrer is right that if the childhood environment were made equally good for all, the only variance in intelligence we’d see would be down to genes.
The real problem, once again, is that we’re far from providing anything like high-quality early childhood care to all, which makes the debate we’re not having about how to give middle-class and poor parents better options all the more important.