In my sport and modern society we covered this pretty in depth. Most of it does stem from the socio economic background of people. But then taking a look at the positions they dominate especially in a sport like football people point out the fact that blacks are mainly RBs, WRs, and DBs and not at the QB position although that is changing. When you see a white RB like brock forsey or white DB like sehorn it isnt the trend so I think people just accept the fact that there maybe be inherent genetics involved in all of this.