EvilGoalie 21
GOLD
sure, but good try. Klinefelters is a completely different topic that involves a mulit faceted treatment approach, if diagnozed early. Often times a boy/man is unaware of having an extra X. Boys/men with Klinefelter are still genetically male. The X chromosome isn't neccessarily the "female" chromosome, it's present in everyone (but you already knew that). The presence of the Y chromosome is what denotes sex, and that is something you can't change. There are studies suggesting the Y chromome see to be decaying over time and may one day become extinct...if that pans out, then we are f'd anyway.
You were the one that brought up biology. I'm not trying to say it weighs in one way or another in whatever argument is going on regarding the NCAA, gender identity, whatever. Genotypically male and phenotypically male aren't the same (ask most KFs who have ever wanted to have kids for example, most are phenotypically sterile). The only point I'd make regarding using genetics as a sine qua non underpinning fairness in sport is how granular do you want to go? If one starts teasing apart the Matthew effect for example (easier in high jump, much harder in soccer) the aphorisms that plague youth sports start meaning even less.