Earlier quoted context omitted.
A genetic test to see whether someone has ancestry from Melenasia or Sudan or Scotland is likely to give a different result than casual visual classification. The latter is what we commonly call "race".
I can tell the difference between German and Irish people at better than chance and you think people can’t tell the difference between Melanesians, Caucasians and Sub Saharan Africans? Bone structure, skin tone, hair colour and hair texture don’t give as much information as a whole genome sequence but telling the difference between an East Asian and a West Eurasian isn’t rocket surgery. By the same token it’s not har…
Get someone to show you pictures and have you identify them. I bet you'll make a lot of mistakes.
Historically, not only can people not tell the difference objectively, they decide what the difference is subjectively. In the United States, the child of a white slave owner and a black slave, if their parentage was known, was ... black. People of "mixed race" might be deemed a different race than their own full siblings, based on which visible characteristics they got from which ancestor.
Even today, people migrating from one country to another are often surprised that their racial classification is different in the new country than at home.