Performance differences between male and female athletes "raise interesting questions about athletes who are genetically rather than pharmacologically enhanced," writes Chris Cooper in an excerpt from his new book, Run, Swim, Throw, Cheat: The Science Behind Drugs in Sport, at The Observer. If female athletes can be disqualified from competitions because they have certain genetic mutations that make them more masculine — here, the author points to the Santhi Soundarajan and Caster Semenya cases — Cooper wonders whether other genetic differences could render an athlete ineligible to compete. "After all, elite athletes are all genetic anomalies — it is just a question of how extreme the anomaly. Will there soon be DNA testing to accompany drug testing?" he asks.