It is simply impossible, and ignorant of the established science, to discount the role genetics play in predisposition of identifiable groups towards either certain abilities and/or limitations. The genetic makeup of ethic groups does affect certain characteristics. While the human genome project is starting to throw more light on the specifics of this, some of it has been known for years. Probably one of the more well known, and unfortunate, genetic dispositions is that found in black Americans with respect to Sickle Cell Anemia:

"Sickle cell anemia affects mainly blacks, though people of South American, Southern European or Middle Eastern descent also are at risk. About one in 500 black newborns, and one out of every 1,000 to 1,400 Hispanic babies are diagnosed with sickle cell anemia each year in the United States. A baby born with sickle cell anemia inherits a gene for the disorder from each parent. Some people inherit only one gene for the disease. This is referred to as having the sickle cell trait. People who have the sickle cell trait don't develop the disease, but they can pass the gene on to their children. Almost 10 percent of black Americans carry the sickle cell gene."

http://www.mayoclinic.com/invoke.cfm?id=DS00324

This simply bolsters what geneman said above.