Is this from real data?

I would think that the behavior of parents has a massive impact on the way the children grow up (but indeed, not the material stuff that so many parents fuss so much over), considering how strong of a correlation there is between the parents' belief systems and behaviors and their children's.

I'm not much compared to even a small survey, but from my small sample I've noticed a possible strong correlation between the way parents respond to questions / handle "problematic" behavior / do anything to "educate" their children and the intelligence, rational behavior and open-mindedness of the children later in life.

The most salient example (but not the most statistically significant) is that everyone I talked to about this who were on the higher end of the intelligence scale had clear memory of their parents responding "I don't know, let's find out" to their curiosity when they were a child, while everyone else I talked to had no such memory.

I think looking into actual pedagogical research results and how to best behave towards children would probably be very high expected utility / value of information if maximizing your child's chances of not being stupid is something you care about.

At the very least, a parent can affect the environmental factors that the book mentioned in the parent post mentions (I haven't read the book, only the abstract) by carefully selecting a good initial environment with these things in mind in the first place.

Obviously also worth looking into is alternative forms of education. Public schools are far from optimal both for social and intellectual development.

If any of this is of interest, I can try to help with some research on it.