My understanding is
If your body produces ova, then you are female; if it produces sperm, then you are male. Then added to this there are hormones which are usually defined as male or female, so for example if a woman has higher than normal levels of testosterone, she may display more male characteristics (being hairy, collecting comics, that sort of thing).
I'm not sure how it works for hermaphrodites though.
( tangledupinblue hairy badge with moving eyes, Fri 14 Oct 2011, 9:45, Reply)