I think I'd need more evidence to take a stand on this one way or another. In general, I'm opposed to forcibly imposing identities on young children in these stages of development, but on the other hand, there's so little evidence on this topic that there's probably a lot I'm not taking into account. Furthermore, there's also the problem of people approaching identity in different ways. Just as with sexual orientations, say homosexuality, you'll have people who live half their lives in confusion before realizing they're gay, and people who'll know the moment they're conscious of sex. Gender identity is probably the same way, requiring a case-by-case basis for judgment. It may be possible that hormonally, or neurologically, this kid has been wired like a girl since birth, in which case, the perception of gender identity might actually be valid to that extent, though that doesn't settle the question of bathrooms and legal issues and so on. It could also be parents going overboard and influencing him, as others have pointed out.