Housemates, science shows, share more than just space. The types of microbes that colonize the gut tend to be similar among members of the same family or household. But where does the sharing begin: through contact, environment, or diet? And do more social factors like status play a role? To find out, researchers recently examined the microbiomes of seven neighboring groups of wild Verreaux’s sifakas in Madagascar. Sifakas in the same group tended to have more similar microbiomes, but differences between groups weren’t explained by differences in diet, home range, or habitat. Maternal lineage was an important driver of similarity within groups and may also explain why adult group members, which are generally less related, shared the least similar gut microbiota. In addition, dominant males had different microbiomes than their group-mates, possibly because of rank-related differences in physiology and scent-marking behaviors. Interestingly, factors like sex, female reproductive status, and faecal glucocorticoid metabolites didn’t account for microbiome differences. Overall, intrinsic and social factors have a stronger impact on gut microbiome variation in this primate species than environmental factors and these findings highlight the sociability of the gut microbiome and how it might influence the social habits of animals and humans.