This should either go in the Spoilers and Speculations Thread or the??Ask a Question, Get an Answer Thread (though I suppose this could be a long discussion). But, to answer your question, my theory is that if, say, a person from the EK (bender or non-bender) and a person from the FN (bender or non-bender) have kids, it will either be a Firebender, an Earthbender, or neither. I doubt they will be able to do both at one time, considering the elemental spirit has to be born into the child. Two non-benders could have a bender for a kid.
Now, since you're talking about the Avatar, he can bend all of the elements, so I would say the kid would be either an Earthbender, an Airbender, a Waterbender, a Firebender, or a non-bender. I would seriously doubt that the kid would be able to multiple-bend, because that would mess up the whole Avatar cycle. If that happened, then if a hybrid Earth/Fire-bender and a hybrid Water/Air-bender reproduced, there would be a whole other Avatar. But, that's just my theory....
Edited on 10/14/2006 10:37pm