Fan Casting Murder in the Family in Sort by Tropes

Familicide, or the killing of one's own family members, especially your spouse, progeny, or parents, has always been viewed poorly in most societies, though in some cases there were exceptions. For instance, in Ancient Greece and Rome the practice of leaving a newborn child to die of exposure if they were born physically deformed was considered perfectly acceptable. It has also served as a method of gaining greater power via getting rid of competition, or for conserving resources in extreme cases during hard times (if the bodies didn't also end up becoming the resources).