What I have come to understand is for bones, it's a game of averages. So amab bones on average might be bigger, or differently shaped or whatever than afab bones across some statistically significant sample for specific bones in specific cultural groups, as an example. Which does NOT mean that any individual bone on any individual person always fits within the expected norms of that statistical sample. That's not how statistics work.

For example if you're digging up bones and you find one bone, that doesn't probably tell you much about who that bone belonged to. If you find a complete skeleton that might tell you more about that one person because you have a bunch of bones, but still isn't 100% accurate. You can't know everything about them with a full skeleton. If you find a pile of bones or a whole city of bones then you can probably tell something about an area or a population group for example but that doesn't mean you can guarantee much else about any individual bone or individual set of bones either. So basically yeah we're all different and just because you can use statistics to derive some useful information it doesn't mean you can use those statistics to derive everything all of the time.

It's the same shit that racists do with crime statistics or economic statistics or whatever. They look at the statistic of a group, they take it out of context for that group, and then they apply it to an individual instead of a group. It's taking data and removing it many steps from reality to intentionally draw wrong conclusions.

So of course they'll do it with shit like bone size or facial proportions or literally anything you can think up. It's not science but since it is "backed by data" it feels legitimate to people who refuse to think about it.