There is a good chance that it's exactly the opposite.

Our behavior is determined by the environment, and there is not element in the environment more important that our peers.

If you take a Roman and a barbarian an exchange them, you get a new barbarian and a new Roman (because how could they survive otherwise?). And, I suspect, if you exchange the Romans and the barbarians slowly enough you will have the previous Romans behaving like barbarians and the previous barbarians like Romans.