I love articles and information about this topic. This Wall Street Journal article really delves into it.
I remember being amazed when I was younger when I found out that people ethnically of the Middle East and North Africa are considered white in the US. I also remember being fascinated with the classification of Hispanic people; how they can be any race.
Mixed race/ethnicity is such a blurred line for many people. Where do you cut it off? For instance, my paternal grandmother is ethnically Bahamian which (on this particular branch of ancestry) is biracial (black and white) with Scottish and English roots (along with the African roots). I like to acknowledge my Bahamian culture and read up on it but I would never say I was biracial or even Bahamian (blog title be damned).
For me, if another race or ethnicity debuted in your ancestry further than great-grandparent status, I wouldn’t claim it. But to each his or her own. Any sociologist/anthropologist will tell you there is nothing biological about race; it is a social construct so people really should not get so hot and bothered over this issue. It is sad when I hear other black people claim they are “mixed” because they are Jamaican and Haitian (for example). People, learn the difference between race and ethnicity first. Be proud of your heritage but it does not elevate you above those who are not sure/cannot be sure of their heritage because of slavery.