Why do the gangs in west side story hate each other in the movie?

In "West Side Story," the gangs, the Jets and the Sharks, harbor deep-seated animosity due to cultural and social tensions, primarily stemming from their differing ethnic backgrounds. The Jets, primarily white, resent the Sharks, who are Puerto Rican immigrants, fearing the loss of their identity and territory. This rivalry is exacerbated by economic struggles and societal discrimination, leading to violence and conflict as each group seeks to assert dominance in their neighborhood. Ultimately, their hatred is a reflection of broader issues of racism and prejudice in society.