I may have misremembered that one, I’ve definitely seen that argument posited elsewhere and around the same time.
I think you may mean androgen there rather than testosterone, but putting that aside, genetic variance is just proof that there are differences between individuals and not that there will be neurological differences split down biological sex. There are, of course, thousands of genes spread across the chromosomes (of which about 1,500 are on the X sex chromosome and a lot less on the Y) and so it makes far more sense that the observable differences relate to specific genes than the more generalised chromosomes.
For approximately 98.3% (or higher, since the 1.7% figure I’m referencing covers more than chromosomal variance) of the population that’ll be 46 chromosomes; those with 45, 47+, chimerism and/or mosaicism are all part of the intersex world. I’m going to assume that, particularly given what little context was available in the Google memo, the intersex variations are not being included in any of this argument, on either side of the debate? Right? Unless, of course, those of you who can point so clearly to what a “male brain” is or what a “female brain” is can also define what an “intersex brain” is and why it is that.
Anyway, XY with the inability to process androgen and testosterone properly such that a female body develops either in whole or in part is Androgen Insensitivity Syndrome, which is split into three main types: Mild Androgen Insensitivity Syndrome (MAIS), Partial Androgen Insensitivity Syndrome (PAIS) and Complete Androgen Insensitivity Syndrome (CAIS). PAIS is what Pidgeon Pagonis has and Hanne Odiele has CAIS. Whereas there are a bunch of other conditions which result in producing less testosterone (as distinct from the inability to process the androgen itself) and some of those are chromosome related (e.g. some XXY people with hypogonadism), but some of them are purely hormonal.
All of these conditions, however, are intersex conditions and not transgender. That being the case I’d be interested to see the details of the case you’re citing and specifically whether it’s actually regarding a transgender person or whether it’s another case of either misappropriation of intersex conditions or conflating the two.
I can accept that a transgender person has a deeply held sense of identity or sense of self which they interpret along a particular gender role or perception of a gender role. This does not necessarily mean that their experience of that gender identity is categoric proof of a biological basis for that gender role. Nor do I necessarily have to accept that any interpretation of gender roles or the societal construct surrounding them must always have greater value than biological issues; or that their experience of their gender self-perception’s ascendancy over their biological sex necessarily means that the same experience for all others requires gender perception to be ascendant over biology (regardless of whether or not that gender perception matches biological sex or not).