Comment by prettyStandard

So I can't speak to this specifically but I think it's well known reading to children when they're young improves their IQ. And that sounds pretty believable to me. In the formative years if you give the brain good info it's going to learn how to operate well. I know this is hand wavy, but I think wealth can be a proxy measure for a good home life in the formative years. So sorry I have no citations, but I find it pretty believable.