We ended up on the appropriateness because you said "If you are suggesting mental health therapy, that has been tried and found to be wanting. [...] The only treatment modalities that are proven to work for trans people are medical and/or surgical intervention."

But I hadn't said anything about mental health therapy! I'd only said, "we mostly don't know which aspects of the process have which consequences for development of gender identity--certainly not in any great detail".

Anyway, because this wasn't supposed to be my point anyway, because we mostly agree regardless, and because you don't seem eager to do so, there's little reason to hash things out further in this regard.

However, I do read the primary literature on functional and structural imaging from time to time. I haven't found the PET study you're talking about (even after looking for it). Could you link to it, please?