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human
[Avatar: The Last Airbender and Legend of Korra] Can benders only be born in their respective nations ?

Is in some way were you are born connected to the type of bending you will receive, like fire benders can only be born in the fire nation, water benders in the water tribes etc. Is in some way your bending associated with the real world borders ? If the fire nation had won and conquered the world everybody that would born in the now world controlled by the fire nation would be a fire bender ? And if you are born in the Replubic City from Legend of Korra since it's a neutral territory you could born with any type of bending ?
gpt
Probably has more to do with genetics than national boundaries 

In Republic City we confirm mixed race couples can produce benders from both cultures represented 

(And Bolin’s unique abilities are not fully explained but may be because of said mixed ancestry)