You really don't have a clue as to what you're talking about. This happened to church-going friends of ours. They had two "normal" girls before giving birth to a third daughter, who, from the time she could talk, insisted to them that she was a boy. The first two girls were actually quite pretty, whereas the third kid looked kinda mannish, and preferred truck toys to dolls. Over two years later, it was time to start Junior Kindergarten. After much anguishing, the parents decided to let her change her name to a boy's name of her choosing, and to identify as a boy in class. Not an easy decision. They did a lot of research, and got the rest of us parents in the community on board. 

The rubber doesn't really hit the road until hormone injections. But there's no question it's a lot easier to transition before puberty than as an adult, so ... we'll see. That's a few years down the road, and who knows what the state of the research will be then.