Of all these alternative theories skull shape/expansion is the only one that makes sense to me and it explains why women and some guys don't experience male pattern hair loss. From my observation skull shape is a good predictor. Guys with big heads, broad sloping forheads almost always are in some stage of mbp. In contrast, those with small heads, low and steep "feminine" forheads and flat top rarely experience any hairloss at all. If they have intact hairline in their late teens they will likely keep their hair. There are exceptions of course. I knew two guys who had small heads and went bald. In both cases their hair loss was aggressive and they were almost completely bald by mid 20s. So this could be a different autoimmune process with acute inflammation. Big headed guys on the other hand usually go through all norwood stages more slowly and this could be explained by the reduced blood flow theory due to the dome shape. Androgens are involved in all scenarios either way that's why hrt may halt or even reverse hair loss in some casese.If it’s skull expansion. Explain how some guys were like norwood 4 and then went to norwood 1 after hrt for a sex change. You saying their hormones shrink their head. I used to believe in the skull theory until I went out and say soooo many dudes with different shapes heads and not one of them was immune from balding. Even looked at photos of skulls that were small and weren’t balding only to find the same shape on another balding