It has been my experience that neither social background nor education has any real impact on intelligence. One's occupation does not seem to predict their intelligence either, though performance in any occupation does. Of course, how long a particular occupation will retain someone of high IQ definitely depends on how interesting that person finds the work and that is quite unpredictable. And, some occupations will be quite limiting for someone without a high enough IQ to perform. For example, you don't find many theoretical physicists with an IQ below 120 though they do come in a wide range of social skill.
Since education, social class and most other environmental factors seem not to have any real effect on IQ, an assertion based only on personal experience, it seems quite reasonable to look for genetic markers. And, since no race is excluded from producing brilliant people those genetic markers must be more basic to humans than are the markers for race. I think the search for such genes is well worth the effort. Note however, that being born with particular traits cannot be blamed entirely on genes. It seems that a great deal of what we are born with is a matter of chance. I'm not even implying environment during development, but rather just chance. I suspect you are born with a particular IQ or g for the same reasons you are born with particular fingerprints.
If I'm right, then a more important question is how to educate people so that we, and they, get the most from what they are born with. I think "no child left behind" should be replaced with "no child's potential left underdeveloped".