Mother was right. Our shoes are filthy, and we'd be smart to leave them at the door, like they do in Japan.
Even microbiologist Charles P. Gerba was surprised to discover what we track into the house on our footwear.
"I'm starting to make myself paranoid," he said. "It seems like we step in a lot more poop than I thought."
Gerba is a professor in the University of Arizona's Department of Soil, Water and Environmental Science. He's spent years studying how humans spread microbes around and "share" them wherever they go.
