I think you get cases where this happens in what if say are "strict gender roll" environments with kids that don't fit the norm and are a bit unbalanced mentally and can't just pretend to fit the norm like normal people do.

I think it's why you see a lot of it come from kids with strict religious backgrounds. Kid might not be gay or anything other than just having more feminine interests than the norm, but if the kid is growing up in an environment where that isn't tolerated I think it can come about as a way to essentially "be themselves" though I don't think the trans identification itself necessarily comes about in those situations until they encounter it later.