This is from Steven Stayner and gives good insight:
"You should know that the first thing abductors often do is convince the child that their parents don't want them. My abductor faked phone calls to my parents. He actually told me he went to court to get legal custody. I was seven. I had nowhere else to turn. I eventually accepted the lie as reality.
"The next stage was adapting for survival. This meant doing anything to avoid punishment. I actually helped my abductor keep the secret.
"So don't expect abducted children to come up and ask for help. They're totally dependent on their abductors. And if they're being sexually abused, which is usually the case, the last thing they want is to draw attention to it.
"I trusted no one. My greatest fear was that someone would find out the truth and confront my 'father'. I didn't know what he'd do. As bad as things were, I knew it could get worse.
"To survive, abducted children must learn to lie. When people would ask me about my past, I made it up. I now assume people knew I was lying, but no one ever tried to find out why.
http://www.stevenstaynermemorial.org/Steven's%20Legacy.htm
Exactly!