Comment I can tell from a CT scan if spanish or hispanic (Score 3, Informative) 144
It's really easy: races are more than skin deep. An african albino has african facial features and we can tell he's not an european.
As a neurologist, I usually look at CT scans, even before meeting the patient. Spanish (europeans) and hispanic (american native or mestizo) people share names that the latter inherited from the former. Still, I was able to know whether the scan of a certain Maria Pérez or Juan Fernández belonged to a hispanic or to a spanish person just by the shape of their skull. Spanish, as most europeans, are meso to dolichocephalic (skull elongated front to back), while hispanics, being long lost relatives to asians, are brachiocephalic (round skull). Africans have the most elongated skull, and between europeans, russians have the most round ones.
Of course that's a simple, one guy's observation from a limited dataset. With a huge dataset it should be easy for a deep learning mechanism to find other variations.
That also tells us that even though race doesn't exist as a genetic category, it's there and it can be calculated.