By Clark Collis
September 23, 2009 at 03:06 PM EDT

Mackenzie Phillips is claiming in her new book, High on Arrival, that on the eve of her 1979 wedding she slept with her musician father, John Phillips. “My father was not a man with boundaries,” writes the actress, who is appearing on Oprah this afternoon. “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.”

Singer-songwriter Phillips was, of course, the founder of the Mamas and the Papas who enjoyed an extraordinary run of hits in the late ’60s, including “California Dreamin’,” “Monday, Monday,” and “Dedicated to the One I Love.” He also co-wrote the 1988 Beach Boys hit “Kokomo.” But Phillips had a number of addiction issues which undoubtedly contributed to the patchiness of his post-Mamas solo career and, ultimately, to his demise in 2001 at the age of 65.

Two questions immediately spring to mind: Given that John Phillips is not around to refute this accusation from his own, much troubled, daughter, do you believe her? And, if so, will you ever be able to happily listen to “California Dreamin'” ever again?

More on Mackenzie Phillips’ book:

Mackenzie Phillips details drug use and incest in new memoir

More from EW’s Music Mix

Glee’s version of ‘Somebody to Love’: Awe-capella!

Miranda Lambert sings you a ‘Love Song’: It’s an EW exclusive video!

New T-Pain track, ‘Dope’: Auto-Tuneless?

‘New Moon’ soundtrack: Hurricane Bells singer explains how he got the gig

Photo credit: John:Ralph Dominguez/Globe Photos; Mackenzie: Richard Drew/AP Images