system
Given the following post, respond as if you're commenting on Reddit:
human
[ATLA/TOK] Would identical twins, triplets or more born of parents or grandparents of two or more different tribes necessarily have the potential to develop completely different bending abilities? I'm working on a story based on the idea of quadruplets masquerading as a single person - the Avatar.
gpt
There’s a pair of twins in Aunt Wu’s village; one is an Earthbender, the other isn’t.

There’s also Mako and Bolin, Fire and Earth respectively while being full-blooded brothers from a mixed-race family; mom was Fire Nation, dad was from BaSingSe. Hell, even earlier, look at Katara and Aang’s kids: one non-bender (gained Air later after Harmonic Convergence), one Waterbender, one Airbender, in that order!

So yes, there’s plenty of precedent for families of varying nationalities to have multiple bender-types, though it would take a few generations for all four to converge.