The "tacking social expectations on top" is the part that is gender!
There's no biological foundation for wearing a sari, hijab, miniskirt, etc. Those are social expectations for women, or part of the role women fill in society.
It's a wholly different concept than biological sex. My penis does not make it impossible to wear eyeliner. But society has a social expectation that I do not. It's not a sex characteristic, it's a gender characteristic.
You might believe gender is immutable. I'm not going to argue that with you. But denying the idea that humans have both characteristics derived from biology (sex) and from societal expectations (gender) is simply objectively incorrect.
> It's not a sex characteristic, it's a gender characteristic.
They're one and the same.
> But denying the idea that humans have both characteristics derived from biology (sex) and from societal expectations (gender) is simply objectively incorrect.
I don't deny the existence of social expectations (you severely misread what I wrote), but those expectations were deriving from the recognition of the objective truth of one's sex. They were never a matter of one's "internal feelings", they were an extension of one's sex.