Spoiler: They aren’t.
The image below is this article summarized in TL;DR infographic format. Though, the article contains a lot of additional information. Feel free to steal and share it. As always, I don’t need any credit.
(Edit 05/05/21): Noticed a typo in the image, corrected now (Norweigan -> Norwegian).
The best study on American genetics is a 2015 genome-wide analysis produced by the Harvard Genetics team, featuring the renowned geneticist David Reich. The study was published in the American Journal of Human Genetics and features a huge sample size of over 200,000 people.
The study found that White Americans are, on average:
- 98.6% European
- 0.19% African
- 0.18% Native American
BUT it also found also found that:
- Only 3.5% of Whites have African ancestry
- Only 2.7% of Whites have Native American ancestry
So, around 95% of White Americans have no African or Amerindian ancestry, and White Americans are only 1.4% non-European, on average.
Compare that figure to some other ethnic groups of Europe:
- Morodovians have ~12% Siberian ancestry
- Finns have ~8% Siberian ancestry
- Iberians have ~5% North African ancestry
- Italians have ~2% North African ancestry
According to US Census Bureau data, the largest ancestries of White Americans are:
- German (13%)
- Irish (12%)
- English (9%)
- Italian (6%)
- French (4%)
- Polish (3%)
- Scottish (3%)
- Scotch-Irish (2%)
- Dutch (1%),
- Norwegian (1%)
- Swedish (1%)
- Russian (1%)
However, many British Americans self-report simply as “Americans” (7%), meaning that the Anglo proportion is likely under-represented.
Here’s the regional genetic breakdown from the Harvard study:
The vast majority of White American ancestry is of Northwest European origin; mostly Anglo-Germanic. As such, White Americans look like pretty average Northwest Europeans (discounting all of the obesity).
Averaged American phenotypes:
Common average phenotypes of Northwest Europe:
Regarding the anti-American “Mutt” slur:
Firstly, all European ethnic groups went through a process of ethnogenesis by mixing with other European ethnic groups. The English are Britons + Anglo-Saxons + Scandinavians, the French are Gauls + Franks + Italians, and so on. Granted, there has been some wacky ethnic intermixing in America since the 1965 Immigration Act, but Americans are still fundamentally Northwest European. If Americans are mutts, then Europe is the #1 mutt zone on the planet, considering how much internal migration and interethnic mixing has taken place within the continent over the past few thousand years. All Europeans are quite literally cousins, and share a common ancestor as recently as 1000 years ago.
Secondly, a huge misconception when it comes to European genetics is that Northern Europeans form radically distinct ethnic groups, on a biological level. Obviously, there are regional variations in phenotype but a Dane, a Dutchman, and an Englishman (for example) are genetically near-identical to one another. To put this into perspective, an Englishman and a Russian are more closely related to one another than a North Italian (Aosta Valley) is to a South Italian (Calabria). Pretty crazy, right?
(Smaller number = more related):
This is partially due to the aforementioned migrations within Europe, and partially because all Northern Europeans derive over half of their ancestry from an ancient population known as the Corded Ware. I’m not going to explain the Corded Ware here, but this 10 minute video is a good introduction.
So, are Americans “mutts”? No more so than other Europeans — but that may change in the future, given the incredibly bleak demographic situation.