The Nurture Assumption: why children turn out the way they do

The way kids turn out depends about half on their genes, and half on the way they were raised, right? Like most parents, my wife and I loaded up on child development books when we had our first baby, and that was the overwhelming consensus. Study after study shows, not to put too fine a point on it, that great parents make great kids, and that lazy, divorced, alcoholic loser parents turn their kids into sociopaths.

Judith Rich Harris is a very brave woman. In the 90s, she decided to write a book that completely upends this mainstream “nurture assumption” and really pissed off a lot people in the process. Ironically, Harris had been cranking out mainstream developmental psychology textbooks for 20 years until she realized that most of what she had been writing just did not compute.

Harris’ big bombshell is that peers matter way more than parents in shaping a kid’s psyche. But what about all those studies? Harris argues that they’re flawed in three ways:

1. Most studies that link parenting to child development don’t control for genetic influence. That means, for example, that aggressive parents could be passing on their aggression genes to their children. The study, however, would just conclude that the aggressive parents are setting a bad example for their kids.
2. Most of these studies are correlational — they measure the relative likelihood of two things happening at the same time, eg. “aggressive parent” and “aggressive child”. That means the causation could go either way: my kid could be aggressive because of my bad example, OR the kid could be aggressive to begin with, and make me more aggressive towards him as a result.
3. These studies inherently assume that parental environment is the whole story: nurture = parenting, period. All the other environmental stuff your kids are exposed to is not taken into account. So, for instance, your kid could be a victim of bullying at school, but the study wouldn’t know that.

A very different picture emerges when you do take those things into account. To simplify in the extreme: all else being equal, kids with loser parents who have a strong, supportive peer group do better than kids with fantastic parents who have a crappy peer group. One huge caveat though: all these factors have to be within normal range. If a kid is being seriously abused or neglected, at home or at school, all bets are off.

The peer group explains a lot of things that the nurture assumption doesn’t. Why do immigrants’ kids pick up the local language so quickly even if their parents don’t speak it? Why is it so hard for parents to change their kids’ behavior, habits, hairstyle and dress code, when usually all it takes is an offhand comment from a couple of friends? And my favorite example: why did upper-class boys in Victorian England end up just like their fathers, even though they only saw their fathers a couple of weeks a year? (Because they went to same boarding schools as their fathers.)

From an evolutionary standpoint, the peer group bias also makes total sense. To succeed as adults (ie. make babies that survive), children will need to cooperate and compete with their peers, not their parents.

Of course, all this shouldn’t absolve parents from doing the best job they possibly can. But if you believe the basic premise, it might shift your focus a bit. Personally, I’m spending a lot more time getting to know my kids’ friends and talking to them about group dynamics.