I just finished re-reading The Nurture Assumption by Judith Harris. It holds up like few other books do. But perhaps the weakest part is her discussion of counter-examples – Traits where parenting does seem to make a big difference. The most obvious is the particular religion you practice. It really does seem like parenting has a big effect here, and Harris doesn’t deny it. But how is this possible? Here’s her explanation:

Some things just don’t come up in the context of the peer group. This is true nowadays of religion. Unless they attend a religious school, practicing a religion is something children don’t do with their peers: they do it with their parents. That is why parents still have some power to give their kids their religion.

But this story suggests a simple test: Go to religious schools, and see whether kids who don’t initially belong to that religion tend to convert. My guess is that this almost never happens. And my wife, a non-Catholic who went to Catholic school, confirms it. In fact, whenever students went to services, the non-Catholics were clearly identifiable because they didn’t take communion. Every week, non-Catholics had to be that horrible thing that all kids fear: different. And yet, different was what they remained.

Bottom line: Religion may be the exception that proves Harris’ rule, but her effort to integrate it into her general theory doesn’t work. What’s really going on?