But the picture is extremely complicated, partly because of the myriad ways microbes can interact with each other. If microbes can influence our brains, could they also explain some of our behavior, including the criminal sort? “Microbes control us more than we think they do,” says Emma Allen-Vercoe, a microbiologist at the University of Guelph in Canada. “For the person unaware that they have auto-brewery syndrome, we can argue that microbes are like a marionettist pulling the strings in what would otherwise be labeled as criminal behavior,” says Prescott. We do know a little about one microbe that seems to influence behavior: Toxoplasmosis gondii, a parasite that reproduces in cats and spreads to other animals via cat feces.