What is it called when a group of people identify themselves based on distinct culture, belief system, religion, or history?

It is called an ethnic group when a group of people identify themselves based on distinct culture, belief system, religion, or history. Ethnic group has been defined as "a socially defined category of people who identify with each other based on common ancestral, social, cultural or national experience." Ethnicity is an inherited status and you cannot marry into ethnicity nor can you adopt it.