Warning: this is disturbing! Mackenzie Phillips, the one-time child star of the TV sitcom One Day at a Time, has just released a book that details her incestuous relationship with her father, John Phillips from the Mamas and the Papas.

Everyone knows that Mackenzie has always struggled with drug abuse and has led a troubling life that has included being arrested and getting divorced, but her new book, High on Arrival, is the first to shed light on what really happened between father and daughter. 

She writes about the time in 1979 when her father first had intercourse with her on the night before she was to marry Jeff Sessler: "On the eve of my wedding, my father showed up, determined to stop it. I had tons of pills, and Dad had tons of everything too. Eventually I passed out on Dad's bed."

"My father was not a man with boundaries. He was full of love, and he was sick with drugs. I woke up that night from a blackout to find myself having sex with my own father. Had this happened before? I didn't know. All I can say is it was the first time I was aware of it."

After this disturbing-beyond-words  incident, Mackenzie was eventually fired from her TV show and checked into rehab to overcome her drug addiction. However, her father decided to go to rehab with her, where, let's just say, Mackenzie was fully conscious when shacking up with daddy. (People)

More Daily Dish: It's a Girl for Sarah Michelle Prinze and Freddie Prinze Jr.