The bacteria that reside in the human gut ("the gut microbiome") are known to play beneficial and harmful roles in human health. Because these bacteria are transmitted through milk, mothers can directly impact the composition of bacteria that their offspring harbor, potentially giving moms another pathway to influence their infant's future development and health. A study of wild geladas (a non-human primate that lives in Ethiopia) provides the first evidence of clear and significant maternal effects on the gut microbiome both before and after weaning in a wild mammal. This finding, published in Current Biology, suggests the impact of mothers on the offspring gut microbiome community extends far beyond when the infant has stopped nursing.