Sex determination from human skeletal remains is most reliable from the pelvis: the female pelvis has specific adaptations for childbirth that distinguish it from the male pelvis in measurable ways, and these distinctions can be assessed with relatively high accuracy from an intact pelvis.

The skull offers secondary evidence: male skulls tend to be more robust, with more pronounced brow ridges and other features, though with significant population variation.

The femur alone — particularly two femora without the femoral heads, which are the most diagnostic part of the bone for sex assessment — is one of the less reliable skeletal elements for biological sex determination.

Femoral length and robusticity correlate with sex, but the correlation is statistical and probabilistic, not categorical.

Populations vary in body size, and what is a large female femur in one population may overlap with what is a small male femur in another.