Psycho IV: The Beginning (1990)

It is highly suggested that the main character had sexual felling for his mother

A woman intends to have sex with a man. We see her undressing. We then see her breasts. She climbs into bed and the man feels her breasts and vagina.

A boy strips off his wet clothes down to his underwear and gets into his mother's bed to comfort her. It it heavily suggested he gets an erection and runs off to his room.

When his mother goes after him, she finds a lingerie magazine in his room and calls him a "dirty pervert," then forces him to throw it in the trash during a rainstorm while in only his underwear.

A woman has her teenage son rub lotion on her legs, then she becomes playful with him and rolls on the floor, tickling him. It is suggested he gets an erection and she feels it because she then becomes furious. She grabs him and tries to brainwash him that he doesn't have "that thing" (a penis) by putting him in a dress and lipstick. Then she throws him in the closet and tells him his genitals are only for "peepee."

A teenage boy is seen shirtless and in revealing underwear several times in the movie.

There is a painting which shows a nude woman. Her breasts are clearly visible.

A boy looks through a peephole to see the blurry outline of a naked man through a frosted shower curtain. The man's pubic region is briefly seen, but nothing can be made out due to the shower curtain.

It is implied that a man and a woman are going to have sex. We briefly see the woman's breasts. We hear them both moaning.

A boy is seen kissing an older woman, quite passionately.

A man and woman are shown having sex. He is seen thrusting on top of her. Both moan. No nudity is shown.

A man is seen lying naked on a bed, with his rear end partially visible. He then gets up and his backend is again only partially visible as he puts on a robe.