Now, I'll grant that he graduated in biology, which means that there's at least something he should know: "mental health" (in fact mental everything) is totally dependent on the biology of neurons and the complex interconnections of them. We know this for the very simple reason that we know how to shut mental awareness down totally, so that we can slice open bodies -- even brains -- without the individual's conscious awareness of it, and bring them back again to their right selves by simply stopping dripping those chemicals in.
Wiring, as in neural interconnection, is physical. It gives rise to mental states, but it is not mental in itself. And if gender perception (like every other perception) is a function of those neural interconnections, then it is perfectly possible that the same body can host the outward physical characteristics of one gender and the neural characteristics of another.
Cultures around the world and throughout history have recognized and come to grips with the fact that there are a few people who are in fat "different:" whose gender identities (mental perception of who they are) do not properly fit their assigned sex at birth. Why is it, I wonder, that modern Americans have so bloody much difficulty with what primitive people could understand?
en.wikipedia.org