I was going to say this, but:

Sex != Gender.

Sex: basically, XX vs XY genetics

Gender: basically, social norms, brain chemistry, hormone levels, which often, but not always, correspond to XX or XY genetics

(lets also simplify out intersex, "hermaphroditic", and various rare sexual chromosomal variants, for simplicity)

You need the brain, the nervous system, the endocrine system, whole bunch of other stuff to even start to try to make that call.

There is a reason the term is 'sexual dimorphism', not 'gender dimorphism'.

We find skeletons of ancient humans, with bones indicating likely one particular sex, but, other cultural markers, grave goods, etc, indicating gender non conformity with the norm for that culture at that time.

Like, thats a huge part of how we know that something like what we now call trans people, or at the very least lgbtq+ people of some kind, have literally existed for longer than written human history.

EDIT:

So, to try to give a tldr:

Skeletal proportions basically do have sexes, excepting pretty rare cases of intersex, non XX or XY situations, or potentially other rare genetic skeletal abnormalities that can make sexual distinction from a skeleton alone difficult, like dwarfism, gigantism, etc.

Skeletons do not have genders.

Just full stop, they don't, you can't figure that out definitively from just a skeleton alone.

Hips, famously, don't lie.