Its great that you taught him so early and that it stayed with him. I find with my boys especially that they wind each other up terrible. They both make sure they do what bugs the living daylights out of the other and there do be mayhem in the car. Its getting so bad we are thinking of trading in our 2 cars to get 1 big 7 seater car so they can have plenty of space to themselves. At the moment the 3 of them are stuck across the back seat together. Picture it, i have Reese falling asleep and ending up falling over with his head on Jake, Jake then freaks and tries to tell me Reese did it deliberatly even though he is asleep. Jake then pushes Reese off him and Reese will say Jake did it to wind him up, then Amelia will join in and either rob Jakes glasses off his face or whatever book or toy he has, he then goes mental with her and when i reach back to get whatever she took she throws it over her shoulder into the boot. Complete mayhem.