European white guys can't be much different genetically from American white guys ~ but plenty of them complete quite effectively with the Africans and African-Americans in the NBA, while there are very very few white Americans doing very well at all. David Lee is a legitimate young star, and then there's Troy Murphy and Mike Dunleavy Jr (solid players but hardly superstars). Steve Nash doesn't count ~ he's from Vancouver and grew up playing soccer...

When I was running high school track, it was pretty obvious that black kids dominated the sprints while us whities had the distance-running events pretty much to ourselves. But then the Ethiopians and Kenyans burst onto the international scene as the best long-distance runners of all. Go figure.

Culture and expectations must be part of the equation, but genetics is part of it too ~ not just the differences between "races" (or nations, or clans, or whatever teminology you prefer for groups of genetically-related individuals) but between individuals as well.