[teamonkey]

Yes, it’s almost certainly linked to quality of schooling and exposure to those types of problems, amongst other things, see the Flynn Effect.

https://en.wikipedia.org/wiki/Flynn_effect

[3cKU]

Access to schooling etc can't be the whole story: "black students from prosperous families tend to score higher in IQ than blacks from poor families, but they score no higher, on average, than whites from poor families".

[tptacek]

So IQ is malleable and SES-dependent and GxE interactions are real.

[3cKU]

No. The first part of that quote is consistent with any hypothesis (G only, E only, G&E), i.e. cannot distinguish between them.