In an interview on NBC's "Today" show, Anthony Castro also said he has nothing to say to his father, Ariel Castro, and will not visit him in prison.
Fifty-three-year-old Ariel Castro is expected to be sentenced Thursday to life in prison plus 1,000 years after pleading guilty last week to 937 counts in a deal that spared him the death penalty.
"I think it's the best possible sentence," Anthony Castro said. "I think if he really can't control his impulses and he really doesn't have any value for human life the way this case has shown, then behind bars is where he belongs for the rest of his life."
Anthony Castro, 31, said his father was violent, and Anthony often cried himself to sleep because he had welts on his legs from beatings. Still, he said, he wasn't prepared to hear the details of what his father did to the women.
"I was shocked because of the magnitude of such a crime," Anthony Castro said. "I don't think I could ever imagine anyone doing that that, let alone to find out it was my own flesh and blood, my father."
Ariel Castro's attorneys didn't immediately return calls seeking comment Monday.
The three women disappeared between 2002 and 2004 when they were 16, 14 and 20 years old. They escaped in May when one of them kicked out part of a door and called to neighbors for help.
One of the victims, 27-year-old Amanda Berry, made her first public appearance on Saturday night when she was invited on stage by rapper Nelly during an outdoor concert in Cleveland.
Another victim, Gina DeJesus, spoke to a Cleveland television station briefly on Sunday, thanking volunteers who are building a 6-foot privacy fence around her house.
Copyright 2013 The Associated Press.