It's been two decades since his death, but Klaus Kinski's secrets aren't staying buried.

The German actor, who died of a heart attack at age 65 in 1991, sexually abused his daughter for 14 years beginning at age 5, Pola Kinski alleges in an interview with Germany's Stern magazine. She goes into further detail in her autobiography, Kindermund (From the Mouths of Children).

Pola, now 60, says her father paid her "to be his little sex object, placed on silk cushions. I kept quiet for years because he forbade me from talking about it," she tells Stern. "The terrible thing is that he once told me that it was completely natural, that fathers all over the world did that with their daughters."

Says Pola, "Whether one believes me or not, this is what happened to me. It's the truth."

The author's half-sister, actress Nastassja Kinski, 51, is "deeply shocked" by Pola's allegations. In the German newspaper Bild, the Paris, Texas star said the news has been "difficult" to accept, but she is proud Pola is sharing her story with others. "My sister is a heroine, because she has freed her heart, her soul and also her future from the weight of the secret," she said.

Klaus -- who also has an actor son, Nikolai Kinski -- is best known for his intense, scary roles in Aguirre: the Wrath of God, Nosferatu the Vampyre, Woyzeck, Cobra Verde and Fitzcarraldo.

Pola says she wrote the book to help "others who have lived through something similar," and also to expose who her famous father really was.

"I couldn't stand hearing it any more: 'Your father! Cool! Genius! I always loved him!' I always replied 'Yeah, yeah.' Since his death this adulation has got even worse," she tells Stern. "When I saw him in films, I always thought that he was exactly like that at home.