The title of my blog post is provocative, I know, but I’m actually just lifting it from the title of a new commentary in the journal Molecular Psychiatry by Thomas Insel, the director of the National Institutes of Mental Health. In his piece, Insel expresses his excitement about a new way of thinking about how genes can contribute to our risk of psychiatric disorders such as schizophrenia. It’s based on an emerging understanding of the human genome that I explored in a recent story for the New York Times: each of us does not carry around a single personal genome, but many personal genomes.

When we start out as a single fertilized egg, we have a single genome.