Scholars from many different areas of study have categorized ethnic identity along two pieces of framework; primordial and situational. Both give us a depiction of how we frame our analysis of ethnic identity.
The primordial argues that people just have an innate sense of ethnic identity, it is something we are born with, this framework is founded upon your instinctive want to associate with your ethnic identity. This type of ethnic identity is impossible to change. In fact it is because of this primordial perspective that there is still a great deal of ethnocentrism and conflict between differing racial and ethnic groups. There is still a sense of pride that is found innately within a person.
The other is situational, which lends to the socially defined phenomena of ethnic identity. The only downfall of situational perspective is that it is constantly being renegotiated, redefined all on the grounds of situational differences. Each group of people will come encounter with different strain of their very own ethnic identity, and then it is up to them to decipher how they will react to their ethnic identity.
Under the broad umbrella of the situational perspective of ethnic identity, there is something called resurgent ethnic identity -- which is the idea that your ethnic identity constantly reemerges with historical events and specific circumstances.
One example clearly defines the idea of ethnic identity resurgence. Many Japanese Americans were imprisoned during World War II, mostly they tried to disaffiliate with their ethnic identity. But as soon as compensation for the mal treatment was requested they all wanted to re-affiliate themselves with their Japanese American ethnic identity.
Same goes for the children of those parents who served time in the Japanese imprisonment camps. Once they heard stories of their parents serving time in a Japanese internment camp, they were all proud of their ethnic identity.
One more type of ethnic identity is just recently making its way in society. Emergent ethnic identity involves the creation of a new ethnic identity based on new groups being formed by one or more ethnically diverse groups. A perfect example: the identity of the "Asian American" is a marriage between two ethnic identities. The term "Asian American" emerged to emphasize the shared experiences and well as the common goal to all be equal.
This is not to say that your ethnic identity has to be transformed to remain part of mainstream society, but it is to say that we can see an ongoing trend ethnic identities growing to encapsulate more than one ethnic identity.
No one wants to be left out of the mix, thus when the opportunity to fight against a common goal presents itself, most people are quick to just on the opportunity. And as they say there is "strength in numbers", the more people you can get together to unite over a common goal, the better chance you will have at reaching this goal.
This goes for anything, so long as you can identity with a certain ethnic identity the more satisfied you will feel by being part of something bigger than yourself.