Originally Posted by DonovanTrent

Actually, it's not that simple. One thing they'd be looking for is at the chromosomal level. Usually, a woman has XX and a man has XY. There's a condition called Klinefelter's Syndrome where the person will have XXY. It happens in something like 1 in 20000 births, if I remember right, and effects the person in varying degrees. Hormone levels also come into play.

I saw a show on this not long ago with a guy who had Klinefelter's, he was married with kids. But he always felt like a woman and ended up transitioning quite easily, all the way through total reassignment surgery. If you saw her before, as a man, you wouldn't know, he looked like any other guy. When you saw her after, you wouldn't know. True they had done a bit of facial work to bring down the jaw slightly, but still, you wouldn't know.