has accused his father, Ryan, of turning him onto cocaine at the age of 13.
In an explosive interview, a bitter Griffin also charged that his womanizing dad encouraged him to follow in his footsteps when Griffin - then just 11 - began having sex.
Now 23, and the veteran of 2 ½ years in a drug-rehabilitation program, Griffin recalled the day he was introduced to coke 10 years ago.
"We were going to a movie and Dad said, 'Let's do a little of this to get us through. It's a long film.' He pulled out some coke, and that was that. I'd smoke hashish before that with him."
"There were always drugs in the house. I was an old hand at smoking pot when I was 6."
"Dad would rather I did drugs with him than with some person I didn't know and perhaps get myself killed," he says. "I think he was trying to prepare me for the atmosphere I was going to grow up in."
"Dad never gave me any fatherly advice about sex, because I was 11 going on 30 and I didn't need it. He just said, "If it fells good, go ahead."'
Griffin claims that these days, he gets no advice at all from Ryan. In fact, he says, they haven't spoken for more than a year.
"He has rejected me and considers me scum," says Griffin. "My own father gave me cocaine and yet he won't take the blame. If he'd given me a stronger fatherly message against drugs, who knows? My life could have been so different."
Griffin - Ryan's son from his marriage to actress Joanna Moore - lived with his mother after his parents divorced. But then her own drinking problems drove him to move in with his father.
"It felt great for a while, but it comes down to the fact that it was all dangerous, all wrong. My father was older and should have known that. The only time he changed his attitude was when I started to do drugs on my own. He realized it was getting out of hand. But he had started it."
He says his wild behavior was partly caused by sister Tatum's success. She had won an Oscar at 9 for her work in Paper Moon, which she co-starred with their father.
"I felt like
a puppy that wasn't petted," says Griffin.