Possibly because many people have looked at the social narratives that they grew up with and concluded that they did not accurately reflect their experience of the world.

true but still why race issues i grew up with many different cultural backgrounds and ethnicities never had issues nor today. is it about misunderstandings or learned and/or brought up that way or trully just the news.

I'm having some trouble parsing your sentence, and do I don't know anything about when/where you grew up that would allow me discuss this in context. This doesn't seem like the place to do a review of the history of race relations in the US, which is a large and complex subject.