"These atoms combine into molecules and cells, including the 30 trillion human cells that make up your body. Every second, you create 25 million of them—replicas produced by the templates of your specific DNA. But those are not the only cells that make up your body. Your microbiome alone has 39 trillion cells of bacteria, viruses, and fungi that live on and within you. You may be classified as a single species, but you are “host” to as many as 1,000. And while your cells hold 20-25,000 genes, your microbiome contains 500 times more. So what are “you” really?"