(Cover) - EN Showbiz - Ryan O'Neal admits he has been a bad parent.

The actor was interviewed on the Today show on Tuesday, after cancelling his appearance on Monday due to ill health.

Ryan has son Redmond with his late partner Farrah Fawcett, who died in 2009. He also has three children from a previous marriage; Tatum, Griffin and Patrick. Apart from Patrick, all of Ryan's children have struggled with addictions, which he blames himself for.

"Looks like it, doesn't it? Sure looks like it," he replied when host Matt Lauer asked if he was a bad parent. "I suppose I was."

Ryan then credited his failings as a father to a lack of being "trained" properly and added that his adult children should now be responsible for themselves.

"Griffin is 45, Tatum is 49, who's the other one? Redmond is 27. They have to take hold of their own existences," he said.

Ryan's son Griffin is in fact 47, while daughter Tatum is 48 and Redmond, 27.

Ryan has just published a memoir titled Both of Us: My Life with Farrah. The 71-year-old star has explained his reasons for penning the tome.

"I wrote it because I missed her, and it was a way to keep the line between us going. I felt that she was nearby when I wrote this, that she was close," he said. "I am not over it yet."

Farrah died at the age of 62 after a long battle with cancer.

Ryan was diagnosed with prostate cancer last month. (C) Cover Media