OK, you don't like yogurt
. Or kimchi, tempeh, sauerkraut or other "friendly-flora" foods. But if your housemates eat them—good news! Their healthy brain-boosting microbes have probably taken up residence in you
. "A number of gut microbes form so-called spores—environmentally hyper-resistant cells that help to colonize them," explains James Scott
, professor of occupational and environmental health at the University of Toronto. They're found on surfaces and in dust; we inhale and ingest them.