[chiefalchemist]

Actually. No.

You need two differnt "widgets" to tango, not three.

Unless you say Sex A and Sex B together is a third sex Sex A+B. But that would only make sense if A+Bs were unique in the sense that they can only mate with other A+Bs. Then A+B would be a third sex. That's not the case, is it?

Put another way, sex is a property, not a class.