Not OP, but have genetics background in other fields (not intelligence). The following is a bit of a mix A way you could look at this would be to think as heri

Not OP, but have genetics background in other fields (not intelligence). The following is a bit of a mix A way you could look at this would be to think as heritability here as the cap of your intelligence. No matter how hard you try, barring some sort of magical medical intervention, your maximal intelligence is limited by your genetics. However, that's the maximum. There are many ways to reduce IQ (lead a famous example here, nutrition another). I think it's not an unreasonable hypothesis that those in lower socioeconomic brackets might increasingly encounter the damaging effects which might have an outsized effect on IQ. More factors than just heritability might create that effect you've mentioned.