I do wonder when it will happen that a male enters a women's race.
I can see the point that gender is social construct--in that perhaps it answers the question what does it mean to be a man or a woman. But sex is biological. Even when people started to differentiate between gender and sex that was the differentiation.
And to preempt the conversation, Caster Semenya is a different story. Even if she has internal testes she probably didn't know for a long time. So it seems to me that she came into the problem honestly. Whether to make her take drugs to compete as a woman has no easy answers. That question, like much of politics, is difficult. People always pose it as one person's rights, but it's really a matter of whose "rights" (desires, in some cases, for know one NEEDS to compete, for example) to uphold. Should you exclude her or make her take drugs to compete, for the sake of other women without her advantages, or should you allow her to compete as she is. It's a tough call. Personally, I'd vote for allowing her the option of taking drugs in order to compete as a woman. If she doesn't want to take them, that's fine, no one is forcing her, she just can't compete as a woman. Yes, its a bad deal for her, but I think it's the best solution taking everyone into account.