You know in the old days when a man went off to war or out hunting meat for the family and was killed it wsa the oldest son who took over. Hi assumed the role of the father and took care of the mother as the dad would and the mother would assume her place knowing that now HE is the man of the house. And even in some instances the boy would take to the mothers bed assuming ALL of the fathers roles and the mother would have no choice but to submitt to her son. In these cases the son would choose his mother to take the role as his wife and the would spend nights of passionate love making amd mother doing as she was told.