I agree that you can't force someone to let go of their heritage and it's a shame that you can't.
I think if we all let go of our heritage and pride in our culture, race, ethnicity, etc., this world would be a much better place. I think that being proud that you are white, black, Chicano,..., is an exercise in absurdity. You basically have pride about a characteristic that is outside your control. It's utter foolishness and the result is people like the one that started this thread.
I think you should only be able to be proud of things within your control. Be proud of your accomplishments, the kind of person that you have become, or decisions you have made. But being proud that you are white, Black, Chicano, is absurd. What role did you play in being born white, Black, Chicano, etc.? None. You could have just as easily been born another race or ethnicity.
For example, where I grew up, there were a lot of people of German heritage. I was always hearing from classmates how proud they were to be German-American because of all the great things the Germans did. I always felt like asking, "How much of a role did you play in all the 'great things' the Germans did?"