But the point is, they start doing that before they even know they are transgendered. They don’t go “oh! I transgendered! Now let me see how everyone thinks girls should act and I will act like that”, I think it is more like they start out preferring girls and then realize later on that they are transgendered.
Sure. As far as they know (with the examples I know), they’re a girl and they have a penis. They’re not trans, they’re a girl. And sure, they’ve heard adults say that boys have penises and girls don’t, but they can look down their own pants for proof the adult is wrong, QED. It’s not until they learn a little more about society works that they identify as trans. Until then they’re just a girl like any other girl. Also, some of the girls with penises like boy things. They’re tomboys. Trans tomboys. It really has nothing to do with what activities you like, although there’s a large overlap.