The line between male and female can be hazy
The Spec
October 24, 2009
http://www.thespec.com/News/BreakingNews/article/657636 (http://www.thespec.com/News/BreakingNews/article/657636)
What's the difference between a man and a woman?
The question seems too silly to be science: Its answer is so obvious that every stand-up comic has a different way of saying it. (Even the gender jokes break down by gender: Male comics say women go to the bathroom in packs. Female comics say men wouldn't understand what they talk about in there anyway.)
But the difference is only obvious most of the time.
In some unusual cases, resulting from sex-change operations or medical conditions, the usual indicators of male and female can contradict each other in the same body. The best-known recent example is South African runner Caster Semenya, who has been put through "gender verification" amid suspicion about her muscular physique and low voice.