Bones: Sweets has trust issues involving finding a home. Since he grew up an orphan, the anger he's sublimated has paralyzed him from developing a healthy perspective on what having a home means. That made him bond with us and our home so he didn't have to deal with his own emotional insecurities.
Booth: Bones shoots from the outside! Three points!
Sweets: Where's that psychobabble coming from?
Booth: Well, you left one of your psychobabble books in our bathroom.