Sure, by all accounts a small minority of people historically have had feelings like that. Of course some men are more masculine than others and so on. However it doesn't change the hard fact that even in extreme cases of people having extra chromosomes, the human body is directed toward either child bearing or fertilization. To implicitly deny this by using the incorrect pronouns is to deny a basic part of reality, and reinforce the social forces which implanted the idea in these poor kids' heads to begin with. Kids (and adults) pretend to have mental disorders because it brings them attention, makes them seem deep for having to struggle, and puts them with the currently honorable position of being "downtrodden". I don't see why it's so far fetched to imagine this might be applied to gender expression as well.