"LOOK UPON THE FACE OF YOUR NEW POPE. HIS HAPLOTYPE IS IRRELEVANT. HIS PERUVIAN HERITAGE ASIDE, LOOK INTO THE EYES OF A CHICAGO SPORTS FAN AND KNOW THAT HE HAS SUFFERED LIFETIMES OF ANGUISH. THE FAILURES OF THE HAM SANDWICH RACE PALE IN COMPARISON TO THE 'DOUBLE DOINK', THE BULLS AFTER THE YEAR 2000, AND THE UNSPEAKABLE TRAUMA OF BEING A CUBS FAN. KNOW THAT I DO NOT SPARE HIM THE JUSTIFIED TRUTH ABOUT HIS GENETICS OUT OF CONCERN, BUT MERELY RESTRAINT; THERE IS NO ADDITIONAL MISERY I NEED TO PLACE UPON A CHICAGO FAN, IT WOULD MAKE ME SEEM WEAK AND OPPORTUNISTIC... LIKE YOU, HAM SANDWICH."
Afaik they use pelvis, though other bones are also used when pelvis is unavailable, this is way less reliable though.
Size itself seems particularly unreliable. Men can be small and women can be large just based on nutrition alone.
Fun fact, when they exhumed general Pulaski remains, they determied he was a trans man.
With the pelvis it's not only size but the shape as well, especially for individuals who have given birth. The pelvis is a more reliable source for sex estimation than the skull, though it is still an educated guess. I would be very suspicious of anyone claiming to be able to determine the sex of any skeletal remains with any degree of certainty
talkin' out my dude ass doo doo ass here but I feel like they probably use literally whatever clues they have available including skull size and shape but probably within the context of as many other things as possible
like I think they kinda just do what they can when they have like half of a skull and a middle finger and they gotta figure that shit out