Science has discovered that, like any work of literature, the human genome is a text in need of commentary, for what Eliot said of poetry is also true of DNA: 'all meanings depend on the key of interpretation.' What makes us human, and what makes each of us his or her own human, is not simply the genes that we have buried into our base pairs, but how our cells, in dialogue with our environment, feed back to our DNA, changing the way we read ourselves. Life is a dialectic.