krou writes "Caster Semenya won the 800m at the World Athletics Championship in blistering style, leaving her competitors in the dust, but she has been thrown into the midst of a scandal amidst claims that she's not really a woman. According to the many press reports, she's believed to shave, is flat chested, has a very masculine physique, previously preferred playing physical games with boys, and shunned traditional female activities and clothing. Questions about her gender have dogged her entire career. Previously, acceptance that she is a women relied on simple inspection of female genitals. But now the IAAF claim that they want to conduct further tests to see if 'she may have a rare medical condition that gives her an unfair advantage.' An IAAF spokesmen noted that 'The [testing] process was started after Semenya made her startling breakthroughs — a 25-second improvement at 1500m and eight seconds at 800m, just some weeks ago.' I'm curious what the Slashdot community thinks: what can be considered proof of someone being male or female? Is it simply a case of having the right genitals, or are there other criteria that should be used? Is the IAAF right in claiming that someone should be prevented from competing because they have a rare medical or genetic advantage?"