So I was playing uncharted3 online and after looking at my custom charcter I noticed that the only way to play a female character was to play Marlow, Chloe, Or Elana and I thought that we should be able to make custom female characters. If anyone else feels this way then please comment so we can see about getting this in the game.
Not gonna happen now or ever sadly. This was highly requested even during the beta stage of the game, but it never happened.
You'll just have to stick with the 3 females that are available.