This is wrong. There are actually chemicals released while developing that cause a brain to start developing more masculine features. Women and male brains are actually different in multiple aspects due to evolutions reaction to the different roles each gender has played in reproduction. Sometimes, this chemical is mistakenly not released, and other times it is released mistakenly. It has NOTHING to do with mental illness. In fact, I don't have anything to back this statement up but my guess would be that if mental illness is involved, it would be because the person lived their whole life not knowing who they are and that itself caused mental illness versus the other way around.