Mr. Schubert says "I am just as certain that my gender is female – and I am sure that my physical sex is male". I understand the reasons for the second of these claims; but about the first, I ask "how do you know?" If Mr. Schubert responds "because I feel it to be so", that is no response since it only reiterates the claim whose basis I am questioning. If he responds "I have always felt myself to be a woman, even though, to all appearances I am a man", I ask "how can you feel yourself to be something which you are not?" His claim is that gender is inherently subjective, but even if i accept that (which I do not, despite the fact that very many people agree with him,) it stills leaves the question of the reasons or the basis for that belief wholly mysterious, even arbitrary, perhaps even delusional. From what he's said, all I can garner is that he believes it because he believes it, which is no basis at all.