Just Plain Neddy

“Remarkably, studies have examined brains of transgender individuals, concentrating on brain regions that, on the average, differ in size between men and women. And consistently, regardless of the desired direction of the sex change and, in fact, regardless of whether the person had undergone a sex change yet, the dimorphic brain regions in transgender individuals resembled the sex of the person they had always felt themselves to be, not their “actual” sex. In other words, it’s not the case that transgender individuals think they’re a different gender than they actually are. It’s more like they got stuck with the bodies of a different sex from who they actually are.”
― Robert M. Sapolsky, Behave: The Biology of Humans at Our Best and Worst