Scientific American recently published a nice phylogenic tree of humankind, The Migration History of Humans: DNA Study Traces Human Origins Across the Continents (sorry, it’s pay-only, but it is relevant and very interesting), that may be of interest to readers of this thread. It shows how different human populations are related both genetically and geographically.
I think the scientific evidence clearly points to the existence of human races, both biological and cultural. There are measurable differences in gene distributions. Where to draw the lines (and how many) is a rehash of the classic biologist debate, Lumpers vs Splitters.
But I think the real issue about “race traitor” is whether there should be any presumed loyalty to others of your race. Why should there be? Few people swear oaths of loyalty to a race. Certainly there are good reasons to work toward the same goals as people similar to you. But I wouldn’t fault anyone for putting their own and family’s interests first.
It follows the same logic after all: if you should display loyalty to people whose only connection with you similar genes/culture, then wouldn’t greater loyalty to those closely related to better? And ultimately, one is most closely related to oneself.