Song_2012_family_study

Human-associated microbial community composition is highly variable across host individuals, but the sources of this variability remain poorly understood. Previous studies have explored some possible contributing factors such as (genetic) relatedness, diet, and developmental stage. A likely additional cause is that our microbial communities are shaped by our unique surroundings, including the individuals with whom we interact at various stages of life. To quantify potential microbial exchange, we surveyed fecal, oral, and skin microbiota from 159 humans and 36 dogs across 60 families consisting of spousal units with children, dogs, both, or neither. Members of the same family, particularly couples, shared more of their microbiota than did individuals from different households, with an especially strong effect of co-habitation on skin compared to oral or fecal microbiota. Dog ownership, but not children, had a significant effect on the extent to which cohabiting adults shared skin (forehead and palm) microbiota, and dog-owning adults shared more microbial taxa with each other than with those who did not. Furthermore, adults shared more skin microbiota with their own dogs than with other dogs. These results suggest that direct and frequent contact with our cohabitants may significantly shape the composition of our microbial communities.