Oppenheimer said he ended up feeling sorry for Hilton as he came to believe that her mother and maternal grandmother pushed her into using the family name and an exhibitionist streak to become a celebrity. "Her mother, Kathy, put her in make-up and allowed her (into) nightclubs from a very young age," Oppenheimer, said.

"I feel sorry for her because in a way she had no chance to do anything else but live the dreams that her grandmother and her mother had for themselves."

Legal warnings from Hilton's mother failed to stop the book and prompted family and friends to come out of the woodwork with their stories, Oppenheimer said. He said he was surprised to find that Hilton's maternal grandmother was the "stage mother from hell," pushing her daughter into a modeling and acting career that never really took off.

Since Hilton hit the spotlight, her mother has appeared as the host on the reality television show "I Want To Be A Hilton" in an attempt to cash in on the fame of the oldest of her four children. But the show was criticized and had a limited run.

"It is a bizarre family," said Oppenheimer. "Behind the scenes her parents were not opposed to (the sex video) because that totally launched her."

Oppenheimer said it was hard to tell if Hilton was real or the invention of a clever marketing team that was aware her "heiress tag" is untrue. She stands to inherit little from the Hilton empire and needs to work for a living.

"Paris will say whatever comes into her head. She tends to make up stories and scenarios. I do wonder if she doesn't live in a fantasy world herself," Oppenheimer said