George Allen, 51, is being investigated by detectives after his 13 year old adoptive son called 911 about 6 p.m. Tuesday to report he had been beaten by him.  Both father and son were charged with sexually abusing other members of the household after detectives began questioning other members of the family.  Allegations came to light that Allen had groped two adopted sons, ages 21 and 24, in the groin, cops said.  Allen was charged at first with assault and endangering the welfare of a minor after the boy reported that he had been beaten in the head for missing school.  The child was treated at Woodhull Hospital for a contusion to the head and cuts on his face.  Later, Allen was charged with three counts of sexual abuse and the 13 year old was charged with fondling a 6 year old boy who was one of two foster children in the household.  Allen's wife, Lilia, 46, was also arrested and charged with endangering the welfare of a minor for allegedly standing by while the beating took place.