By Richard Dawkins writing for Areo
Race is very much a spectrum. Most African-Americans are mixed race, so there really is a spectrum. Somebody who looks white may even call themselves black, may have a very slight [African inheritance]. People who have one great-grandparent who is Native American may call themselves Native American. Sex on the other hand is pretty damn binary. So on the face of it, it would seem easier for someone to identify as whatever race they choose. If you have one black parent and one white parent, you might think you could choose what to identify as.