What I've learned from all of my years of watching TV and movies is that people in the olden days couldn't tell the difference between a man and a woman, and all a woman had to do was cut her hair short and wear men's clothes and she'd be accepted as a woman.
I'm playing Assassin's Creed 4 at the moment (£4 on sale) and there's a character that's quite clearly a woman (looks like one, voiced by one) who you're expected to believe is a man until the big and not at all surprising reveal halfway through the story.
I remember hearing (on QI, I think) that they used to hold the pope aloft on a chair so that they could check he had testicles. I think it's bollocks though.