Yep. Occam's Razor.
But ok....my thoughts on why, assuming it is nature. Environmental stress on the mother while in the womb could certainly explain some of it. In the plant world the right kind of environmental stress can cause a previously female seedling to turn male, because males can typically handle a stressful environment (famine, drought, etc...) better. Pollution (most common modern stress factor) being ruled out for our ancestors...other stresses still existed obviously. I know my mother had a serious flu when pregnant with me...a possible example. It's also a matter of species survival that there be variation in the population, if we are all the same we can be wiped out more easily. Intersex and nuerologically intersexed conditions fall into the category of beneficial variations I would think? Sorry if that's choppy I'm tired
