Take adopted negroes for instance; Black children raised from infancy by White parents begin trailing academically by age 8.  Why is that? You're right, genetics play a huge role in how the child will turn out academically. However, there is a very small percentage of blacks (3% or so) who have IQs over 120, which is widely considered gifted. Out of those 3%, 70% came from middle-class families. Only 16% of blacks with IQs under 75 came from middle-class families however, so environment is also a slight factor. Still yet, there are far more gifted whites than blacks, and genetics is a huge explanation for that gap. Unfortunately, we gifted blacks are so rare that it can't raise the black IQ average by much.