THE INFANT microbiome, the community of microbes living in a baby’s gut, is crucial for immune, metabolic, and digestive development. Peer Contact and the Infant MicrobiomeIn a detailed study tracking gut bacteria in babies, families, and nursery staff, researchers found that baby-to-baby transmission plays a major role in shaping the infant microbiome. Antibiotics, Siblings, and ResilienceThe study also highlights factors that influence how the infant microbiome develops. This fast recovery was more pronounced in babies than adults, underlining both the vulnerability and adaptability of the infant microbiome during early life. Real-World ImplicationsOverall, the findings reposition social interaction as a central driver of infant microbiome development.