We can’t see them, but they are all around us. On us. In us. Our personal microbes—not to mention those in the environment around us—have us outnumbered by orders of magnitude, but scientists are only beginning to understand how they influence our health and other aspects of our lives. It’s an increasingly hot area of science, though, and this past year saw lots of interesting developments. Here are some of the highlights. When you move, your microbes move with you In a study published in Science in August, scientists cataloged the microbes of seven families, swabbing the hands, feet, and noses of each family member—including pets—for six weeks. They also collected samples from doorknobs, light switches, and other household surfaces. Each home had a distinct microbial community that came mostly from its human inhabitants, and the scientists could tell which home a person lived in just by matching microbial profiles. Three of the families moved during the study period, and it only took about a day for their microbes to settle in to the new place. As the journal’s editors put it: “When families moved, their microbiological ‘aura’ followed.” Microbes could help solve crimes Scientists made several findings this year that could potentially show up in court one day. One study found that the microbiome of human cadavers evolves in a predictable way, hinting at a new way to determine time of death. And earlier this month, researchers suggested that bacteria on pubic hair could be used to identify the perpetrators of sex crimes—especially useful when a rapist uses a condom to avoid leaving behind DNA evidence. Your gut bacteria may be inherited Exactly which bacteria choose to take up residence in your gut is determined, in part, by your genes, scientists reported this year after examining more than 1,000 fecal samples from 416 pairs of twins. Identical twins, who share 100 percent of their DNA, had more similar populations of gut microbes than did non-identical twins. Moreover, some types of bacteria seemed to be especially susceptible to the genetics of their human host. One of the most heritable types was a family of bacteria called Christensenellaceae, which are more abundant in lean people than in obese people. When the scientists inoculated mice with these bacteria, they gained less weight and put on less fat than mice without the bacteria. The researchers suggest that one way your genes influence your chances of becoming obese is by shaping your microbiome. 6 More via WIRED.