Here is an interesting fact: your body contains more microbes than human cells. You are not just a single genetic individual you are a living colony, sharing your life and space with millions of other life forms.
If you watch crime programmes on TV you will know how often people are convicted on the basis of matching DNA to samples of body tissue found at the crime scene. Your DNA is like a signature on each of the cells in your body. The microbes that share your body do not share your DNA, they have their own DNA. This is how we know they are not human cells. Generally the microbes are friendly towards us, they help keep the gut free of pathogens and some are able to feed on our waste products (like cellulose) producing small sugar molecules that we can absorb.
It makes you think – you are not just responsible for yourself but for all your fellow species colonising this shared space we call our body.