The_last_airbender
in simple terms the lion turtles are masters of energy bending and imprinted a kekkei genkai of one of the four elements Into humans who left their back in the ancient times that passed down to their descendants of those that didn't have the imprint retrieved when returning to the lion turtle, kinda like the x gene in marvel being shortcuts of what sorcerers have to train to do but they do it instinctually (at least for those that connect to dimensional energies)