Predicting others' feelings is a superpower that enables efficient social interactions. How do infants learn which emotions precede and follow each other? We propose that infants develop this ability by tuning into the dynamics of their socio-emotional environment. If so, we expect that the way in which infants process emotion transitions will reflect both general patterns seen in adults as well as local statistics of observed emotion transitions. We measured 4-10-month-old U.S. infants' (N=70) pupillary responses to emotion transitions and surveyed primary caregivers on the frequency of their own emotion transitions. As expected, infants were attuned to adult patterns of emotion transitions, showing greater pupillary synchrony for frequent transitions. They were also sensitive to their caregiver’s specific transition frequencies, exhibiting similar pupillary responses to infants whose caregivers show similar patterns. These findings suggest that infants learn about emotion dynamics by observing statistical patterns in the people around them.