re: Are their genetic differences between races? Or is it environment?

Probably some variances in inclination, but largely situational factors have shaped modern man.

Obviously, there is something to the fact that most great long distance runners are of East African descent, most great sprinters are of West African extraction, and look at how well Asian students do, despite recent arrival status and language barriers?

On the other hand, environment does play a big role. White suburban kids who start playing tee-ball at 4 or 5 make up the larger population from which MLB are drawn - that's not genetic, that's environment. The better physical specimens are screened in, genetically, from this base population (and of course, Central/South America, Japan and Korea all have huge population of baseball players). Flip that - what did inner city kids have for decades? Shoes, bball and and a basket. They didn't have access to swimming pools, baseball parks or football equipment. Thus the overwhelming demographic advantage that remains in basketball today. It doesn't hurt that most African Americans are of West African descent and have a slight genetic advantage in running and jumping, generally.

To ignore these is to be naive. On the mental side, it gets dicey - Jews - not strictly a race, but an insular population, to a certain degree, for example, are overrepresented among Nobel laureates. Perhaps it is related to their doing a little better, financially, as a group in pre-WWII Europe, but it continues in the post-war populations of Israel and the U.S.

So, without getting into various racial supremacy nonsense or otherwise judging people based on immutable circumstances beyond the individual's control - it is very likely a combination of factors - the DNA forms the "infrastructure" (the building and physical plant, itself, if you will) and experience and environment fill that building (the people, furnishings and content of that building, if you will).