And I would still ask the question: how many generations removed from the ghetto are these black children, on average? That environment can take generations to overcome in terms of child development. Furthermore, what is the culture within the family? Is it still "black" poverty culture? Also, were those kids in the upper middle class families born into that class, or did their families fight their way there during their childhood?
The bottom line is that we're still talking environmental and cultural factors, here. Those need to be fixed before we see real improvement.
Why is it a matter of dogma for you that all differences are due primarily to culture or environment? Is it really your contention that some people aren't born with innate talent, while others are born innately incapable?
For instance, I have zero musical ability, not due to lack of trying. If I was adopted at birth by a virtuoso musician couple and immersed in music, there's no doubt I'd still be terrible at it.
Similarly, a black child with an IQ in the 80's adopted by a wealthy, educated family and given every opportunity in the world will still have an IQ in the 80's. He might do better socially because he won't be drawn into a life a crime (or is less likely to be), but he won't become talented by osmosis.