Does everyone have a sertain kind of worm or should they not be there?

Not in America. In the United States, people are not supposed to have any worms inside their bodies. If a person has symptoms suspicious for worms, his doctor will look for parasites and use medication to get rid of them. Rarely, there will be dormant (not active) parasites that are too hard to get rid of. A primary care doctor can order stool lab tests to look for worms and their eggs.