Or to keep the gods from visiting destruction on the area because of their incest?
Oh no, they killed their healthy child in a ritual sacrifice to show off for the neighbors. That makes SO much more sense.
Human sacrifice was going on everywhere centuries ago for all sorts of reasons-none good-people were ignorant-and if they envied or feared you, they might leave you alone-or they might sacrifice or kill you one way or another. The druids burned people in cages-and the Spanish Inquisition tortured all non-Catholics-most to death, people in Europe and the New World burned people they called witches and heretics, etc, etc...