A custom (also called a tradition) is a common way of doing things. It is something that many people do, and have done for a long time. Usually, the people come from the same country, culture, or religion. ... Many customs are things that people do that are handed down from the past.
50 years ago certain radio stations only played certain kinds of music and they were lumped together, not by genre, but by ....... You fill in the missing blank.
Now tell me, what do jazz, blues and Gospel have in common?
Once a tradition is started, it just carries on beyond the time that anybody knows why?