The Hero is said to bear a birthmark in the shape of the Triforce. In most lifetimes, it is on the left hand. In others, the mark is more... oblique.

"You say you bear the mark of the Goddesses," Princess Zelda said, "yet I see no mark. Please, show me the proof of your fate."

"'Kay." was all Link said before tipping their head back and pulling at their nostril.