A mutation tied to the soil...No, genetics. It must be in the genetics. Tell me, are these-- what do you call them -- nonbenders more prevalent or less? Is it more likely that two nonbender parents would have a nonbender child?

A-- [And he was about to ask another question, but what she said next worried him. Airbenders were down to a single family?]

Was there some sort of extinction event for airbenders?