Many people put a lot of stock in their bloodlines. They like to tell tales of famous ancestors and are excited to learn that their great-great-great-uncle performed a heroic deed. I find this tendency rather curious. Why do we care so much about the lives of long-deceased people we’ve never met, simply because we inherited some of their genes? Do we believe their greatness has been passed down to us? What about the ancestors with less admirable stories — do we believe we inherited the shame of their misdeeds? (And if we go back far enough, aren’t we all part of the same family tree?) Whatever the reasons, there’s no question that our biological and genetic descendancies form key parts of our identities.