laradorren replied to your post:I came across a debate about what kind of bender Asami would be. One group said she'd be fire because her linage can be traced back to the fire nation on her fathers side. The other group argued airbender because she's calm, soft and doesn't like to fight. They also said heritage isn't that important compared to personality. Even said maybe she could have some airbending ancestors (What? is that even possible?). The first group said if anything personality is influenced by the type of bending.
Good point about the need of being temperamentally suited for bending apart from genetics. Maybe when it comes to bending it is like 60% proper heritage and 40% right personality? that would explain why Katara is bender (with non-bending parents)
I don't think it's quite so simple as a percentage split, honestly.
The way I think of it is, heritage produces potential. If you don't have the right heritage to bend an element -- at least one parent with an ancestral connection to that element -- you cannot, under any circumstances, bend it.
It's somewhat unclear, however, how that interfaces with the individual's genetic code. DNA clearly still offers nothing more than potential, given that we've seen identical twins with different bender statuses, but whether an individual born from parents with ancestral connections to an element can be completely barred from bending it because they lack the proper sequence of proteins in their genetic code is impossible to tell.
What seems obvious is this -- the trigger that determines whether a bending-capable individual realizes that potential or not is experience-based. It could potentially be epigenetic in nature and hence factor in ancestral experience as well as individual experience (which could feasibly avoid the "proper sequence of proteins" issue entirely), or it could just be an interaction between the individual's genes and their own personal experience, with no impact on their children's genetic inheritance, but in either case, the trigger is useless if the proper heritage doesn't exist.
Personally, I like the idea of a two-tiered pseudo-epigenetic system of bending inheritance, with the ability to produce bending children being triggered by cultural connection and the ability to bend being triggered by individual affinity. It would explain why all Air Nomads were airbenders (every Air Nomad parent had the cultural connection pattern triggered, and every Air Nomad child had their individual affinity pattern triggered by their upbringing) as well as why Tenzin produced all airbending children while Aang did not (Aang and Katara each had different cultural connection patterns triggered, while Tenzin had the air pattern triggered and Pema's inherited non-air pattern was never triggered because she felt more affinity with air). It could also explain why the Fire Lords never really had to worry about non-bending heirs no matter who they married, why there were towns/boroughs that seemed to be entirely comprised of non-benders, why benders could be born of non-bender pairs, why non-bending children of two benders were rare but not impossible, and why the Southern Water Tribe apparently went from one bender in the entire tribe to a sizable fraction of the populace being benders in three and a half generations.
