We, as humans in our varied cultures, have made it more than chromosomes. Your chromosomes don’t determine how you’re expected to look and dress or how other people react to you. That part is indeed a social construct that has changed in different places and times.
I think this also addresses Annie’s question. Nobody is traumatized because their last chromosome has or doesn’t have that second “leg” that differentiates an X from a Y. Heck, given that many people who have come out as trans in the last few years are perfectly fine not having “bottom surgery,” it’s not necessarily even their genitals they are confused or bothered about. (Heck, that’s the basis of the entire restroom/locker room panic, right? I presume people wouldn’t be concerned about “men” (trans women) sharing space with cis women if they didn’t have penises.)
The thing trans people want is precisely the “outward appearance” element — to be acknowledged and treated as their internal gender, and permitted to look and dress and act as such. Not being beaten up/killed/driven to suicide on the regular would also be nice.
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