Update: Some people are taking this post as a criticism of 23andMe. Really it’s not. It’s just to point out that customers sometimes overinterpret the granularity of these regional tests. There just isn’t the power to discern between British and Dutch too well (there are other ways to do this genealogically….). And, it really matters in the case of Afrikaners since their Dutch (and German and French) national origins are well known.
In my post below on the non-European ancestry of Afrikaners, several readers mentioned that friends of Afrikaner background were rather chagrined to have reported British ancestry from genetic tests. The cultural reason for this is well known: many Afrikaners exhibit hostility toward British imperialism due to the deprivation and death which was the consequence of their resistance to the expansion of the Empire during the Second Boer War. This is above and beyond the antipathy which was manifestly made obvious by the fact that with the transfer of the Cape Colony to the British in the early 19th century thousands of white farmers migrated into the hinterlands to escape the new power (in part to preserve their customs, such as slavery).
By the 20th century, this anti-British aspect of Boer identity manifested itself in pro-German sentiments, as can be seen in the film The Power of One.
But the reality is that it is strange for Afrikaners to have British ancestry. Yes, they are not exclusively Dutch, with substantial German and French (Huguenot) components in their background. And there has been some recent intermarriage with English speaking whites. But presumably that’s recent enough that people would know.
Rather, I think what is happening is that genetic tests do not have the power to distinguish well between English and Dutch ancestry. In fact, the minority ancestry from Anglo-Saxons in southeast Britain would have stronger affinities with the Dutch than most of the island.
To figure out what was going on I asked people on Twitter for 23andMe profiles. I got a response from someone whose results I posted above. This individual has Boer ancestry, mostly Dutch, going back to the late 17th century on his mother’s side and late 18th century on his father’s side. And you see 17% “British” ancestry. He also provided his wife’s 23andMe output. Her ancestry dates back to the late 17th century on both paternal and maternal sides, so it is not a surprise she has more non-European ancestry:
She is 18% British. In fact, the European ancestry fractions of both these individuals are rather similar when it comes to “French-German”, British, and Scandinavian. I suspect what we’re seeing here is what the algorithm pops out quanta wise for Dutch.
I took the South African individuals who had some non-European ancestry, and ran them on Admixture and projected a PCA with British and Dutch individuals. You can make your own judgment, but I think these are definitely people who are of mostly Dutch ancestry.