Is there evidence for this?
Source: http://www-personal.umich.edu/~bbushman/PSPB02.pdf http://blog.uwgb.edu/alltherage/four-questions-on-the-cathar...
Still, if micro-aggressions aren't checked, it is easy to assume they are accepted. That will lead to an escalation of aggression like the GP described.
Probably not.