Perhaps more than at any other time in contemporary history, we have a deep need to understand who we are, what tribe to we belong to, and how, in a rapidly changing, interconnected and homogenized world, do we fit it. Who are we in relation to everyone else.

Just look at the advertising for home DNA testing and you’ll get the idea. Since it’s less clear everyday, where we are going, it feels most comfortable to look back at our ancestry and at least be clear about where we came from and how it defines who we are.

The problem is, that’s complicated to. Who we are is the result not just of our DNA or our heredity, but of an array of complex and shifting forces that we also have no control over. This is the reality that Carl Zimmer explains in She Has Her Mother's Laugh: The Powers, Perversions, and Potential of Heredity