Jest Chillin
Member
And this is why I think they went the way they did. Their spawn would've broken the universe. The same could be said for Tenzin, Kya & Bumi as well. There are a lot of things dealing with bending and genetics that may never be explained but need some light shed on the subject though.
My brother brought to my attention as to why characters such as these can't bend more than one basic element. In the place of keeping the Avatar special and the cycle I do understand but when the previous Avatar & THE WATERBENDER have children and they can only bend one element that does come off a bit suspect though.
It's not suspect at all. Think of it like Eye Color. Bending is like a Gene, so it's a crap shoot. That's how benders are born to non-benders and non-benders can be born from benders. Having two benders as parents make it more likely that the child wil be a bender but they'll still only inherit the ability to bend one thing.