Rising to power in the wake of the Classic Maya collapse, Chichén Itzá was among the largest and most influential cities of the ancient Maya, but much about its political connections and ritual life remain poorly understood. In a new study, researchers discover a practice of ritual child sacrifice focused exclusively on males. Close kin relationships, including two pairs of identical twins, suggests a connection to the Maya origin myths of the Popol Vuh. Further comparison to Maya populations today reveals the genetic impact of colonial-era epidemics.