In any sort of work on sports performance and gene science, race inevitably looms in the background. To his credit, Epstein doesn't shy away from discussing race, but neither does he channel Al Campanis (who infamously blundered into the subject with the sensitivity of a drunken rhino). As the sprinting vs. long-distance running example mentioned above demonstrates, people from different parts of the world excel at different types of athletic competitions. Epstein points out that the individual record for the 100 meter sprint in Kenya isn't good enough to qualify for the Olympics; as dominant as the Kenyans are in the distance events, they're totally uncompetitive in the sprints. Epstein doesn't say this explicitly, but what I drew from the book is that when we Americans talk about "race" and sports, we do so in a very obtuse way because we lump people into "white," "black," "Latino," or "Asian," when in fact there can be a significant amount of diversity within those crude racial categories.
If there's a book that The Sports Gene reminds me of, it's Jared Diamond's Guns, Germs, and Steel, which similarly examined race and cultural through a completely new lens (of geography).