He'll never get to live in my house again. You already have a tremendous investment in your son. If you don't give him another chance, I'd say you have everything to lose. Lance's parents saw my point. They realized their son was not a piece of plastic that could be stamped out perfectly the first time through the mold.
Human beings have a way of taking a long time to work off the rough edges.
What Lance's parents needed was patience and, along with that, the courage to be consistent, decisive, and respectful. One of the best ways to respect their son was to treat him as an adult, even at times when he acted like a small child. Eventually, it would pay off.