Cohabiting family members share microbiota with one another and with their dogs. A study analyzed the microbiota of 159 individuals and 36 dogs across 60 families, focusing on fecal, oral, and skin microbiota. The results showed that household members, particularly couples, shared more microbiota than individuals from different households, with stronger effects on skin microbiota than oral or fecal. Dog ownership significantly increased shared skin microbiota in cohabiting adults, and dog-owning adults shared more skin microbiota with their dogs than with other dogs. These findings suggest that direct and frequent contact with cohabitants may significantly shape the composition of microbial communities. The study also found that skin microbiota were more similar within families than between them, with the strongest effect on skin. The microbiota of infants and children were relatively similar to those of adults, suggesting that the composition of intestinal microbiota changes with age in a way different from skin and tongue. The study highlights the role of shared environments and contact with pets in shaping microbial communities, and suggests that skin is more influenced by environmental factors than gut or mouth bacteria. The results have implications for understanding the impact of lifestyle and environment on human microbiota, and may inform strategies for managing microbial communities in health and disease.Cohabiting family members share microbiota with one another and with their dogs. A study analyzed the microbiota of 159 individuals and 36 dogs across 60 families, focusing on fecal, oral, and skin microbiota. The results showed that household members, particularly couples, shared more microbiota than individuals from different households, with stronger effects on skin microbiota than oral or fecal. Dog ownership significantly increased shared skin microbiota in cohabiting adults, and dog-owning adults shared more skin microbiota with their dogs than with other dogs. These findings suggest that direct and frequent contact with cohabitants may significantly shape the composition of microbial communities. The study also found that skin microbiota were more similar within families than between them, with the strongest effect on skin. The microbiota of infants and children were relatively similar to those of adults, suggesting that the composition of intestinal microbiota changes with age in a way different from skin and tongue. The study highlights the role of shared environments and contact with pets in shaping microbial communities, and suggests that skin is more influenced by environmental factors than gut or mouth bacteria. The results have implications for understanding the impact of lifestyle and environment on human microbiota, and may inform strategies for managing microbial communities in health and disease.