However, totally agree that it is good to be able to experience a multitude of people and benefit from the relationships, just not to lose identity and try to become someone else in order to fit in.
I was just about to write this same thing. There's a difference between getting along with others and pushing one's self under so as to be (falsely) accepted for someone one is not. The former is smart and healthy; the latter is often unhealthy and can lead to serious problems.
Getting along is good. Experimenting with roles one could choose can even be good when one is a child. But trying to be something different--someone less capable--because one is not accepted as one is is not usually healthy.
It's a continuum, of course. But if I saw my child "pretending" to be less capable, I'd be nervous, too! It seems to me the reason why the pretending is happening is the key. If it's a response to teasing or to feeling out of place, then that's a problem. If it's just an experiment, spurred only by the child's observation of those around him, then I'd be less concerned.
FWIW...
