"The human genome codes for approximately 23,000 genes, yet some experts have suggested that the total information coded by the human genome alone is not enough to carry out all of the body’s biological functions. A growing number of studies suggest that part of what determines how the human body functions may be not only our own genes, but also the genes of the trillions of microorganisms that reside on and in our bodies."
"The genomes of the bacteria and viruses of the human gut alone are thought to encode 3.3 million genes. 'The genetic richness and complexity of the bugs we carry is much richer than our own,' says Jayne Danska, an immunologist at the Hospital for Sick Children Research Institute in Ontario, Canada. 'They serve as a buffer and interpreter of our environment. We are chimeric organisms.'"