People in the US have to move fairly often for graduate school, jobs, etc. While some subset of the groups you're seeing are childhood friends, a large number of the people you're seeing have probably not been friends…
I think you'd enjoy this philosophical dive into why we have categories and how to properly use them. http://slatestarcodex.com/2014/11/21/the-categories-were-mad...
People in the US have to move fairly often for graduate school, jobs, etc. While some subset of the groups you're seeing are childhood friends, a large number of the people you're seeing have probably not been friends…
I think you'd enjoy this philosophical dive into why we have categories and how to properly use them. http://slatestarcodex.com/2014/11/21/the-categories-were-mad...