Even if you live by yourself, you do not live alone.

In a recent analysis of dust samples collected from 1,200 homes across the United States, researchers report that most of us cohabitate with a few thousand species of bacteria and about 2,000 species of fungi.

But don’t reach for the scrub brush and disinfectant.

“I don’t want any readers to be paranoid about this,” said Noah Fierer, a microbial ecologist at the University of Colorado, Boulder. “Most of the organisms are completely innocuous, and some may be beneficial.”

In a paper published in Proceedings of the Royal Society B, Fierer and his colleagues report that these microscopic communities can also reveal telling details about the people they live with.

The specific composition of a home’s bacteria community changes depending on whether there is a dog or cat in the household, as well as the ratio of men to women in the home. The composition of the fungi community can suggest what climate and geographical region a person lives in.

“If you want to change the types of fungi you are exposed to in your home, then it is best to move to a different home (preferably far away),” the authors wrote. “If you want to change your bacterial exposures, then you just have to change who you live with.”

Los Angeles Times