In her new memoir, High On Arrival, former child star Mackenzie Phillips writes about the drug-filled life she lived as the daughter of a rock star.

Mackenzie — best known for her role as Julie Cooper on the CBS sitcom One Day At A Time, claims she had a decade-long sexual relationship with her father, rock icon John Phillips, and that he taught her how to do drugs. John, who died at the age of 65 in 2001, was the leader of the 1960s group The Mamas and The Papas.

Mackenzie wrote in her book: “I woke up that night from a blackout to find myself having sex with my own father.”
She says she later confronted her father about the first encounter, which she described as rape.

“My dad said, ‘Raped you? Don’t you mean when we made love?’ And in that moment I thought, ‘Wow, I’m really on my own here,’” Phillips said. She learned to turn her anger toward herself and “boxed it away” rather than think about the drug-fueled incest.

The incestuous relationship later became consenual and went on for 10 years. Mackenzie ultimately ended her sexual relationship with Phillips when she became pregnant and feared her own father had also fathered her child.

Two of Mackenzie’s stepmothers refuse to believe the shocking revelation.

“I am stunned by Mackenzie’s terrible allegations about her father,” Genevieve Phillips, who was married to John from 1972 to 1985, said in a statement to Oprah on Wednesday. “I would often complain to John about her overly familiar attitude towards him and he would tell me that that was just her way. John was a good man who had the disease of alcoholism and drug addiction. He was incapable, no matter how drunk or drugged he was, of having such a relationship with his own child.”

Michelle Phillips, who joined then-husband John in the ‘60s rock group The Mamas and The Papas, says Mackenzie told her the news in 1997 – but later recanted.

“She called me back and said, ‘You know I’m joking,’” Michelle told The Hollywood Reporter’s Roger Friedman on Wednesday morning. “I said it wasn’t funny. Mackenzie said, ‘I guess we have different senses of humor.’”

“John was a bad parent, and a drug addict. But [expletive deleted] his daughter? If she thinks it’s true, why isn’t she with a good psychiatrist on a couch?” Michelle said. “Mackenzie has a lot of mental illness,” she added. “She’s had a needle stuck up her arm for 35 years. She was arrested for heroin and coke just recently. She did ‘Celebrity Rehab’ and now she writes a book. The whole thing is timed.”