People shun others for many reasons ranging from shame and jealously to racial and cultural bias, notes Psychology Today. Shunning has been explored in literature throughout history as exemplified in Nathaniel Hawthorn's Scarlet Letter, and it has been repeatedly displayed in human culture, across societal boundaries throughout time.
The act of shunning is social or mental rejection, describes Psychology Today. Sometimes it can occur for a reason as minor as one party not having the time to stop and speak with another person. The person being avoided can then think that the person doing the avoiding is unfriendly or a snob.
Shyness is another reason Psychology Today lists as a reason some people shun others. In this case, the person doing the shunning actually needs the social connection and misses out on valuable opportunities to connect with other people.
Yet another reason why people shun others is that people tend to group together with other people who are like-minded or similar to themselves, notes Forbes. This can happen anywhere there are groups of people. Some people even hide preferences and affiliations to avoid being excluded from groups and office cliques. Cliques can tend to lack diversity, and clique members frequently leave out members who refuse to join, Forbes explains.