Former child star Mackenzie Phillips will be a guest on Oprah today to talk about her new autobiography “High On Arrival” — and specifically, about her incestuous relationship with her own father. Feel free to stop and shudder with revulsion right there. Star Magazine says

She writes that she was 19 when her dad John Phillips — from the ’60s band Mamas and the Papas — slept 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,” writes Mackenzie, who was already a heavy drug user. “I had tons of pills, and Dad had tons of everything too. Eventually I passed out on his bed… I woke up that night from a blackout to find myself having sex with my own father. Had this happened before? I don’t know. All I can say is it was the first time I was aware of it.”

Their sexual relationship continued, she reveals in the book. She traveled with him and his new band, they did drugs together went to rehab together and — shockingly — even talked about running away together.

“One night Dad said, ‘We could just run away to a country where no one would look down on us,” she writes. “There are countries were this is an accepted practice.”

Jesus, there’s no reason to leave the country just to have sex with your child. Just buy a double-wide and move to West Virginia. Done and done. You don’t even have to burn any air miles!

Dita von Teese promoting her new Wonderbra because it’s not incest:

Where I’m from, you know what they call a girl who can outrun her brothers? A virgin. I guess AnnaLynne McCord’s sisters are natural sprinters.

In Malibu yesterday:

PHOTO SOURCE: Pacific Coast News

Oscar winning actor Morgan Freeman’s divorce from his wife of 25 years just got really ugly — accusations that he indulged in a decade-long affair with his own step-granddaughter are raising some serious eyebrows. The National Enquirer says

E’Dena Hines is the granddaughter of Morgan’s first wife, Jeanette Adair Bradshaw, and was raised by Morgan and Myrna “since she was a little girl.”

The relationship between the 72-year-old actor [and his 27-year old] step-granddaughter began when she was a teen.

“[When E'Dena] was a teenager, she and Morgan went to dinner at a friend’s house one evening. Both had been drinking, and when they returned home, Morgan attempted to have sex with her. They stopped just short of having intercourse,” the source, a close family insider [said].

Unbeknownst to [his wife], the relationship continued for years. E’Dena has also been Morgan’s escort to several public events.

“Nobody thought anything of it, because she would be introduced as his ‘granddaughter.’ It’s not technically incest, because they are not related by blood…[but] Morgan is trying desperately to keep his divorce out of open court so all the shameful facts won’t become public.”

The great thing about incest is that it virtually eliminates that awkward “getting to know you” phase. Plus, if either one of you ever needs a kidney, chances are good that you’ve already got a match. That’s what you call a win-win, baby!

E’Dena at the Dark Knight premiere with Grampy Mo: