[genocidicbunny]

But they do look at bones and near-bone tissues, which can still have variance based on ethnicity and gender. For a really brute-force example, just think about how we use the shape of the pelvis and some other bones to identify the gender of skeletal remains of a person. If you had a data set of pelvic xrays that only included males, your data set would imply that female pelvic bones are massively malformed despite being perfectly normal for that gender.