I think identity is a pretty foundational concept within epistemology itself. The nature of personal identity is a very complex topic that nexuses on a lot of tricky issues. But none of these concepts require property as a concept. I can assign an identity to my cat, by giving her a name. I can assign identity to you even, by giving you a number that I put in a database -- as governments and businesses do! But I assume the *kind* of identity you're talking about, is your intuitive sense of self -- what you might think of as your unique essence of sorts. What David Chalmers tries to grapple with in his theory of consciousness, in what he describes as the "hard problem". Now, I'm with Dennett on arguing this problem doesn't even exist and "qualia" is an illusion, but none of these concepts of our own sense of identity implicate property rights.