Three genders, weird?

Haha, there was a star trek episode on that theme. Thought I'd throw that out there.

That would make the dating process a little more laid back, in my opinion. You could go out for dates in twos for a third person, and it'd feel a little freer.

Regarding life as we know it, I don't think that any species has required more than one partner to reproduce. I think that if a third gender existed, it would be able to sexually reproduce with either a man or a woman, or both, but would never require all three. It might even be asexual, which wouldn't require a partner at all.

But I understand your point: be glad that you only have to seduce one person and not two from different genders!

It would be utmost impossible for the whole thing to work. The first pair would have to agree on the third. It's hard enough as it is to find the one person to be with who likes you. Now you'd have to find two people who not only like you but like each other. In theory your idea works, but with how you've done the xzx, xyz, and xzz, you have a possibility of getting more than just 3 options. You would be able to get xxx, xxy, xxz, zzz, xxy, and probably other combinations. Now the xxx combination could be fun. But the zzz would be a bored. But anyway, you couldn't add the third chromosome and only get 3 genders. That's why with the current system of xx and xy, there are only the 2 combinations.

Wow, I stand corrected, you can imagine 3rd gender species. But who has sex with who? Great imagination.

There is. It's called being a hermaphrodite. The best of both worlds. But other than that, your question is nonsense.

I don't know if you know about this, but there is a type of disorder called intersexuality, which you might find interesting.

(i copied and pasted the below two paragraphs, as it explains better than I would)

Intersex is a general term used for a variety of conditions in which a person is born with a reproductive or sexual anatomy that doesn't seem to fit the typical definitions of female or male. For example, a person might be born appearing to be female on the outside, but having mostly male-typical anatomy on the inside. Or a person may be born with genitals that seem to be in-between the usual male and female types for example, a girl may be born with a noticeably large clitoris, or lacking a vaginal opening, or a boy may be born with a notably small penis, or with a scrotum that is divided so that it has formed more like labia. Or a person may be born with mosaic genetics, so that some of her cells have xx chromosomes and some of them have xy.

Though we speak of intersex as an inborn condition, intersex anatomy doesn't always show up at birth. Sometimes a person isn't found to have intersex anatomy until she or he reaches the age of puberty, or finds himself an infertile adult, or dies of old age and is autopsied. Some people live and die with intersex anatomy without anyone (including themselves) ever knowing.

If you watch the tv series "house". There was an episode of a "girl" who turned out to be a guy. She looked female on the outside (breasts etc), but on the inside she was male.