Heck, if we're going to do one of these we might as well start with the nutty one from the 80s. Featuring Nurse Ratchet as Grandmother Ratchet. They actually had to tone down the incest from the novel, because apparently there's an acceptable level of incest for a PG-13 movie and the novel went just a wee bit over (though there are still plenty of icky hints of a relationship between the older brother & sister).
A lovely story about a woman who has 4 children as the result of an incestuous relationship with her uncle who then goes to live with her insane fundamentalist mother who hates her and locks the kids in the attic because her father will only give her money if she pretends her kids don't exist. Then she slowly poisons the children with arsenic cookies because she wants to marry a new guy. Whippings, incest, sibling blood feedings, bedpost beatdowns and a hanging ensue. FUN FOR THE WHOLE FAMILY!