The lynchpin in Caplan’s case that “parents don’t matter” is the evidence from twin/adoption studies. I confess I haven’t delved into them yet, but my arms’ length understanding is that if you look at identical twins who are raised by different families, and then again if you look at children who are totally unrelated genetically and yet were raised by the same parents, then it looks like parenting has very little to do with how the kids turn out.
So here’s my question: On both ends of these studies, we are looking at parents who adopted a kid who wasn’t their biological child, right? I mean, if you’re studying identical twins, then at least one of them is raised by a non-biological parent, and maybe both. And then on the other end, you’re clearly studying adopted kids.
If so, then doesn’t that represent just about the biggest bias in the study you could imagine? What Caplan is saying is that if we focus on people who go out of their way to amplify their parenting on the world, AND whom the relevant authorities deem as worthy parents, then we don’t see much difference in the effects of parenting on the kids.
I would be much more interested in the results of a study that randomly took kids and assigned them to different households. Of course, I would rather remain ignorant than having someone carry out such a study.