After reading this article (thanks so much for the link), it occurs to me that if our sense of respect, reputation and reciprocity are based on a biological foundation, then that would account for the range of behaviors that we see.

People are different. Genuinely different. Not just in our hair color, height, skin tone or other external characteristics, but in our mental makeups as well. Personality tests attempt to categorize us and we may disagree with their assessments or their rationales, but they demonstrate this fact.

I believe that things like color-blindness, a talent for music or our sexual preference are determined or influenced by genetic factors, which means that they are susceptible to genetic variation.

This genetic variation might explain how some people are touchier than others.

At the same time, our sense of outrage may be cumulative, like our stress response. Repeated hits to our sense of respect, reputation and reciprocity may provoke reactions, even in response to minor offenses.

I'm rambling, but these are some of the thoughts that the article provoked.