the student teacher in my economics/government class told the class that there are 6 different genders, depending on what sex chromosomes one posesses. One of the combinations he mentioned was YY, but if a zygote ended up with 2 Ys, would it develop at all? I would think that there's too much 'stuff' on the X for anyone to survive without one. And any comments on the first part, about there being 6 genders, are most welcome as well.