Lately, we've been learning more and more about the teeming masses of bacteria inside our bodies - essentially trillions of tiny organisms that make us sick and keep us healthy.
Now two scientists at the University of Colorado have dared to ask what kinds of bacteria lives inside our mouths. And they're finding some pretty surprising things in there.
Ken Krauter, a professor of microbiology, and Simone Stahringer, a graduate student, took oral bacteria samples from 45 sets of twins and sequenced the bacteria's DNA. They thought that identical twins would have similar types of bacteria living in their mouths, because identical twins share the same genetic make-up.