To recap: Don’s real name is Dick Whitman. His prostitute mother died in childbirth; his dad, her john, beat him. His fundamentalist stepmother called him a “whore’s child.” Then his father got kicked in the head by a horse, and the stepmother moved in with her sister, herself a prostitute, living in a brothel. The stepmother, heavily pregnant with Don’s half brother, prostituted herself to her brother-in-law, as the teen-age Don knelt outside her door. He watched them, through the keyhole, have sex. C’mon, now. This is no longer the backstory of a serial adulterer; it’s the backstory of a serial killer.