Unfortunately this is very true. In most child sexual abuse cases the abuser is a family member or someone close to the family. To top that off it's usually someone no one would suspect - the reality of someone so close to you being an utter monster, hiding in plain sight, is too much for the family members to comprehend. It's much easier to blame or not believe the victim than accept the inevitable consequences which may involve the law, strained/severed familial relationships as well as the reality that someone vulnerable was hurt badly. Very sad situation for the victims.