I'd suggest reading this article: http://www.slate.com/id/2178122/entry/2178123/
"white kids from households with annual incomes of $20,000 to $30,000 easily outscore black kids from households with annual incomes of $80,000 to $100,000."
In an adoption study where black and white babies were both adopted by high IQ white parents, there was a one standard deviation difference ( 15 IQ points) between the black and white children.
If you are trying to chalk up these differences to some kind of genetic disparity, that in fact Has Been Said, repeatedly, for hundreds if not thousands of years, continues to be loudly parroted by certain segments, and has been repeatedly shown to be uninformed swill.
Why don't we see any discussion here about differences in IQ scores of people from different economic classes, in a nation where opportunity (and even access to healthcare) is so disparate between races?