SS turns 18 in a couple months.  He's autistic, and has never been held accountable or pushed, at all.  I know that sounds like I'm being unkind.  But he really is never held to any standard.  He can back talk, blow up, make up lies, get violent, and there are no consequences for his actions.  It's all swept under the rug at home.  suck your thumb?  That's ok, someone will love you for exactly who you are.  Still eat you boogers?  Just wash your hands after.  Threaten to kill yourself?  Call the cops and go to the ER but absolutely nothing after that.