>>720136536
My thought exercise was about which situation seemed to make more sense.
Buddhist temples recruit kids for various reasons so surely they do so in the show as well.
You're asking for impossible proof, since the argument we're having wasn't a subject matter in the show they were not concerned with providing clear examples of non bending dudes in those temple scenes. Though if i were to open an episode right now i could find you a picture of a monk not airbending or whatever.

On the other hand. There are repeated examples of bending being tied to: life philosophy, chakra, behaviors, past events, imparted training, spirits, celestial fucking comets. All of these non-physical.
The only bullet the genetic theory has is, and hang on your undies everyone because it's a fallacy:

Benders are tied to specific geographic locals, therefore since race is also tied to geographic locations, and race is genetic, then bending must be genetic as well.
That is the pinhead foundation upon which the entire theory stands like an inverted pyramid of self deception. Later canonized by the writers and then reabsorbed by the fans in a fateful feedback loop.

>>720136785 Have my answer.