In primitive human societies, if a baby was malformed or unwanted it would be abandoned and left to die.
In other primate societies, as well as human history, when males conquer a new territory the suckling infants are killed so the females regain their fertility sooner.
In this society, a person must reach the age of 18 before being granted full rights and responsibilities. Before this point, parents are responsible for punishing their children and can legally take actions against children that would be forbidden against an adult.
I'm not sure what the point is. Maybe just that societal norms define what we consider to be moral or immoral, that the example of nature is brutality, that it is our prosperity that enables us to even have these conversations.