Incest scene in Psycho IV?

There was incest going on, and to me, it seemed that the mother/aunt was punishing Norman for it sometimes. Like she was angry she couldn't cross the BIG line with him. Like when Chet spends the night and the next morning, he's talking about the only time a man should be naked in front of a woman is when they have sex. Well, the mother/aunt gives Norman this look like, 'You see, I let him do things with me that I won't let you do.' or something along those lines. Plus, it seems to me, that she was being overly sexual with him. The scene with the whatever oil or water. Man, I almost jumped out of my seat because I wondered if they were actually going to go at it. Norman definitely got a 'hard' problem when he was on top of her and she noticed it. That's why she dressed him as a girl and said she was going to make him forget he even had one. A penis. But she should have thought. He's a teenage boy, who doesn't get much girl interaction and no father or father-figure to explain any of this stuff to him, and even if he did. He could not stop from getting hard when his body was close to another's and they were very close.