This is the function of mythology and tragedy. The story of Oedipus, Medea (who kills her children), or Atreus (who feeds his brother his own children) allows a society to collectively gaze into the abyss of the primal taboo, scream, and then reaffirm the boundary lines of the human.
Eating one’s own kind is perhaps the most visceral of all taboos. It is the ultimate erasure of the "other." To consume a human is to deny their humanity, reducing them to mere meat. It blurs the line between hunter and hunted, breaking the sacred covenant of the tribe. It is the act that signifies the total collapse of empathy. primal taboo
Why is this so primal? Evolutionary biologists point to the —a psychological phenomenon where people who live in close domestic proximity during the first few years of life become desensitized to sexual attraction. Reverse this: siblings raised apart often feel intense attraction upon meeting as adults (genetic sexual attraction). The taboo exists to override a potential biological imperative. This is the function of mythology and tragedy