The only reason would be that the vertical distance between the cheekbone and the eye is less on most women, if indeed that is the case. Most of us mount a shotgun with our cheek bone just above the comb. If the distance, vertically, to the eye is more, the drop must be more. If the distance is less, the drop must be less.
My eye must be a loooong ways from my cheekbone. I just can't shoot many Italian O/Us, because of the skimpy drop. A distance of 1/4" too little is a huge amount, 1/2" is a mile. This is why, for the vast majority of good shooters, it is easier to shoot a gun with a bit too much drop than one with too little. It's just unnatural to have to float a target or bird way above the muzzles. IMHO.
SRH
