Humans tend to think in terms of in-groups and out-groups. In-groups are those who feel an association based on some variable that can be the county they live in or even the sports team they root for. You may feel an affiliation for someone you normally would not because they join your in-group. For example, if someone from a different religion joins your softball team. Today we look at this concept more closely. Here is a good reference for more information on in-groups and out-groups.

https://ethicsunwrapped.utexas.edu/glossary/in-groupout-group