When I was little, most of the books and videos about holiday traditions that I was exposed to at home and at school gave the impression that at the very least a majority of African Americans celebrated Kwanzaa. And not really knowing any African Americans due to the homogenous nature of my school and neighborhood when I was a young child, I assumed this was the case until I was at least a teenager. When I explained this to a black friend in college, he looked at me like I was crazy and told me he had never celebrated Kwanzaa and didn't know anyone who ever did.
Welcome to liberalism. When I was growing up in school each year we recycled info about the underground railroad only to find it nearly irrelevant to today's events. Would have been much better off learning about WWII or the Cold War.