Night Virgin (1974)

The bizarre Arif family usually stay holed up in their old house... for good reason! The clan includes a daughter who's nearly catatonic during the day but a nympho at night, a son who's a violent bully, another son who's a sex maniac and a psychologically abusive matriarch who's both an aunt and a stepmother to the children because she murdered her own sister and then married her brother-in-law. A psychology student who's looking into matters has his work cut out for him.