Originally Posted by HowlerKarma
Only kids with high-enough SES get to meet their potential. The rest struggle to meet SOME of it.

Yes, exactly. This is true of anthropometric characteristics (height, weight, etc). I suspect that it's also true of cognitive ability. And I also suspect that incremental generational gains in cognitive ability may occur if successive generations of a given family or population live in advantaged circumstances. This is certainly true of things like height.