bending involves both genetics and spirituality, but even if you are not so "spiritual" the bending is still there, it is just how you hone the bending.
i realize that people used to energybend, then the influence of the bending arts came from a source that is mostly seen in the persona's culture.
what i realize was that each bending art is more diverse and divided as it develops. but like Guru pathik said "The greatest illusion of this world is the illusion of separation. Things you think are separated and different are actually one and the same. even the separation of the four elements is an illusion. if you open your mind, you will be able to see that all the elements are one. Four parts of oneness."