I may be projecting here but your nephews, if they are like some of my relatives, may not be neurotypical (for example they may have Aspergers disorder). If this is the case their behavior may be better understood in that context that a social one.
My friend's brother is like this. It's pretty obvious upon talking to him that he has some kind of atypical neurology but his parents completely refuse this, and thus keep him trapped in his little bubble without getting any help.
