The Guardian is giving us some pre-London-Olympic buildup, including an interesting article about the impact of strategies to make female athletes more like males: "The rise of performance-enhancing genes".
While not necessarily agreeing with this statement quantitatively, qualitatively it is sound. Female world and Olympic records set prior to random drug testing have been much harder to break. For example, while there is a steady progression in the male Olympic athletic records, there are as many female Olympic records still standing that were set prior to 1990 as those that were set in the last decade. It is hard not to argue with the implication that the steroid doping that was widespread in the 1980s has had a more dramatic effect in female sport than male sport.
I also did not know the story of Dora Ratjen, a gender-ambiguous German athlete and 1938 female European high jump champion.