i think its a really interesting take though. the idea that it is two gaussian distributions that overlap in the middle. because there are indeed some men who have higher pitched voices, lower muscle mass, higher estrogen, lower body hair etcetera, but they are considered "men" but it makes more sense to see it as a point along a sort of gaussian. of course i might be talking out of my ass, but surprisingly i've never heard of a similar take before. because everyone makes it seem as if "sex is biological" and "gender is created" but sex might be ill defined.
There's really very little; it seems like most of the lit on intersex phenomena comes from an angle of eugenics - from a mental gender pov there is an author whose name I forgot who does integrate some studies of intersex people in his work but I forgot the name, I know his entire publishing history is on this stuff though. Will tell you when I remember it.