He can to a point, but once he gets tired / bored the behavior comes out even in public.

Yesterday my wife took the kids to the beach and tried to get a photo of the three of them together. In the sequence you see him pull our 3-year old down and then start chewing on his fingers while he's smacking our 1-year old in the back (not hard but quick repeated pats). The last shot is him staring at the camera with his fingers in his mouth and his other hand hitting the side of his head.

It's an incredibly sad photo for my wife and I to look at. He's obviously tormented by something internally but nobody we've worked with has a clue what it is or how to help him cope with it.