Question: what percentage of our bodies is made up of these independent organisms?
Answer: Your body is made up of about 100 trillion cells, but of those only about 10 trillion are “human.” Cue the X-Files theme song. No, we're not carrying around extraterrestrial DNA. The rest of the cells in our bodies — some 90% of them — are made up of viruses, bacteria, fungi, and other microorganisms.