The Savage Is Loose (1974)

In 1902, John, his wife Maida (his real-life wife) and their infant son David are the only survivors of a ship that crashes into the rocky beach of an uncharted island during a violent storm. By 1912, David, now a seemingly happy 12-year-old boy, begins to enter puberty. By the time he is 17, he is consumed by lust for his mother, which drives a wedge between him and his father to the point where they hunt each other down for the affections of the only woman on the island.