I suggested looking and comparing the magnitudes between different factors and putting them into order of importance.
We know that taller people have higher intelligence than shorter people on average [1]. Compare effect sizes between black and whites and tall and short white males. Now ask if the difference between ethnic groups is important or not.
[1] : https://en.wikipedia.org/wiki/Height_and_intelligence
ps. 90% of genetic variance in human races exists in the African continent. If we clean out all environmental factors, the "smart genes" are probably in Africa. We just need to find them and distribute them.