That's a great point Iolan.
There's the story of a kid near St. Louis who was gone for a very long time.
Shawn Hornbeck had been missing for over 4 years - even watching himself on America's Most Wanted with a neighbor at one point and denying that it was him. Police found him while looking for William Hornby who'd been missing for 4 days or so. He would have had a number of opportunities to leave. His mom/stepdad devoted their lives to missing children after his abduction and he even posted to their message boards/web page twice - using his real name at least once.
At some point I'd imagine Ben [isn't that the brother's name?] might get fed up but I'd be afraid that he'd fight back and, not knowing his own strength, kill his non-bio dad [would it be his stepdad? if his parents were married, he'd be the legal dad? adopted dad?] and that would be a Very Bad Thing.
Anyway - as soon as you said that, I thought of them
.
Carol