[nhchris]

> many studies have shown that when correcting for socio-economic factors (e.g., wealth, quality of education, lead in drinking water) there is no difference

Could you share these studies? Though I worry correcting for "quality of education" involves grouping by schools that use the SAT as admission criterion, which is close to correcting for intelligence itself.

One could also flip it around - if IQ is "fairly" rewarded by income, then one would expect the differences to disappear if you correct for income. It's basically saying that people of equal IQ get, on average, equal income. Unless one holds a truly extreme blank-slatist view of people, that implies discrimination is negligible.