The Myth of Pure Blood

Apparently there is some question as to whether George Washington’s family tree was lily white after all. White people often raped slaves*

What’s crazy, to me, is the idea – held by many in 2016 – that there are pure populations. Of any humans. I’m not a population geneticist, but my understanding is that if you’ve got a population and you add another population to it, within a fairly small number of generations, they’ll eventually wind up producing a new population that shares most of

Your pure blood probability chart

Your pure blood probability chart (source)

the genes of the original populations – especially if those genes don’t reduce fitness somehow. This is in accordance with the Hardy-Weinberg Principle, which appears to my non-geneticist eyes to be a straightforward application of statistics, allowing geneticists to reason about the proportion of alleles in the population over time, given a certain genotypic frequency and population size. You can simulate the effects of a new genotype coming into the population by watching the probability certain alleles will be expressed over time.  I think I’ve got that right (I expect the commentariat will correct me if I’m wrong!)

So, I got into a “friendly discussion” with a xenophobic racist, who offered the view that he was of “Pure English Blood.” Of course, I asked him what that meant, and he explained that his family were English as far back as could be, and hadn’t interbred with any (whatever)   I tried to break it to him gently** that it didn’t matter whether his family were “Pure English Blood” if they bred with anyone who wasn’t – which included anyone whose ancestors’d bred with anyone who’d bred with anyone whose ancestors weren’t “Pure English Blood.” I let that sink in for a little bit and then mentioned that England had, at various times, been overrun by Danes, Romans, the French, and Americans. So I asked him how he was sure that his great-great-great-grandwhatever-to-the-N’th hadn’t had a bit of a Roman holiday behind the woodpile? And, if that were the case, maybe he was part Italian. Or maybe a viking*** paused between looting and pillaging to do a bit of raping before they burned things. “We could be related, cuz.” I told him, then he blocked me.

As Van Halen said:

You can’t get romantic on a subway line
Conductor don’t like it, says you’re wastin’ your time
But everybody wants some
I want some too
Everybody wants some
Baby, how ’bout you?

Van Halen was clearly right. When we look at the genetic shadow cast by Niall of the Nine Hostages, it’s pretty clear that Niall wanted some, and got it, and:

Early in 2006, geneticists at Trinity College, Dublin suggested that Niall may have been the most fecund male in Irish history. Of their Irish sample, the geneticists found that 21 percent of men from north-western Ireland, 8 percent from all of Ireland, a substantial percentage of men from western and central Scotland, and about 2 percent of men from New York bore the same Y-chromosome haplotype. The geneticists estimated that about 2–3 million men bear this marker, and concluded that these men are patrilineal descendants of Niall. (wikipedia)

Pure blood is a myth

Pure blood is a myth (source)

The same can be said of Ghengis Khan, who – well – if you’re from any part of the world that the Mongols rode over, you’ve got a good chance of having some of the great Khan’s genes. When the Great Khan wanted some, he got. One in 200 men is a descendant of Ghengis Khan, which gave my internet “Pure English Blood” friend a better than lotto chance of being part Mongol. Personally, I’d think that’d be pretty cool. After all, conquering peoples tend to spread their genes pretty lavishly, which means that we’re descended from a great line of conquerors!  Conquered, too, if you like that.

Understanding of population genetics also ought to put to bed any claims of “ancestral lands.” Because, you can pretty much pick your ancestors, and say “Oh, yes! Ancestral lands!” Since I’ve got some Irish in me, and some Norwegian in me, and some other random American stuff in me, I’m probably part whatever I feel like I want to be. Do I get to claim my homeland north of Dublin, Ireland, or do I get a piece of the middle east? I may have some indigenous peoples in me on my great grand-mother’s side, but nobody ever knew for sure, or cared very much. Is Lyle, Wisconsin my “ancestral home” or is it Hell, in Norway?**** The “ancestral lands” issue is, of course, a big problem, when you have a racist state established on the myth of blood-lines in the middle east. Conflating cultural artifact (tribe) with racial interpretation (blood line) can lead to some horrible, violent, errors. The Nazis were as wrong about their ideals of racial purity as they were about the idea that a population could exist within other populations for thousands of years, and still be a blood-line at all. I’d bet that a lot of those Nazis were descended from Mongols because: 1 in 200.

People who imagine they’re pure blooded anything are living a racist fantasy (or they’ve mistaken racism for classism, which happens because they tend to go together) that utterly ignores the reality of conquest and human mixing, which is how humans have, you know, made humans for a very long time. You don’t have to go far back, either – World War II was a massive gene-mixer, especially in the parts of Europe that the Red Army marched across (though the Wehrmacht were no slouches in the burn, loot, pillage, rape department) (and the GIs were pretty skilled at wartime “romance”) (etc.) – there were rapes, and war brides, and casual flings, and the great big melting pot of humanity got another big stirring. It’s not just the winners’ raping-sprees, but the losers, as well. I occasionally wonder if the real concern some Europeans have about the refugees pouring in from Libya and Syria is that their “pure” blood is going to get admixed, as if the turmoil from WWII wasn’t enough. But they should remember – some of those Syrians and Libyans are certainly descended from Romans and Crusaders (and Mongols, of course) – they are little bits of DNA returning to their ancestral lands.


A funny thing happened a few years ago, I was in Ireland and made a point of visiting the (known) ancestral homestead. And, as I got to a pub and was drinking a cider, I asked if there were any McGroders around, because I was an American who was part McGroder and I’d come by on a lark. And one of the locals looked at me, “McGroders? Around here, we call ’em ‘The Danes’ because they’re all tall and blonde if y’know what I’m sayin’.”*****


I was initially a bit thrown by the “Niall… most fecund male in history” because that didn’t seem to line up with Ghengis Khan 1 in 200. Then I realized that Niall (600AD) had a 600 year head-start on Ghenghis (1250AD), so the shadow he cast was longer, proportionally. Do we measure these in terms of overall percentage of population? Niall wins with 20% to Ghenghis’ 0.5%!  Or do we measure in terms of global population of descendants?

(* The article says:

As slaves, the women could not consent to the sexual advances of the plantation owner’s adopted son, but Kunkel said she tries not to think of the acts as rape.

“I try to focus on the outcome. He treated Maria with respect after the fact,” she said.

I probably don’t need to say anything further about that.)

(** That’s a lie. I’m sorry. “I tried to break it over his head” is more accurate.)

(*** My Norwegian ancestors were always fishermen. So I am told. But it’s nice to be able to play the “viking card” occasionally.)

(**** I do get to say “my people came from north of Hell.” Which is some kind street cred or other.)

(***** I heard a really funny joke about that, but I’m not sure I can type it in, because it depends on pronounciation. So here it is:  WARNING: mildly “ethnic” but appropriate in this context



  1. cartomancer says

    Minor correction – Niall is earlier than 600AD, with Celtic historians unsure whether to date him closer to 400AD (as most of the chronicles do) or later to around 450AD. Genghis died in 1227, which is closer to 1250 but still shy of it.

    I encountered this sort of thinking last night, strangely enough. It was at a pub quiz, where a question was asked about the third most common language spoken in England (after English and Welsh) according to the census. We were tossing up between Polish and Urdu, and eventually went with Polish (correctly as it happens), on the logic that the majority of Pakistani immigration to the UK was decades earlier than the majority of Polish immigration, and second and third generation immigrants tend often not to speak the languages of the places their parents came from. It was only in the car on the way back that I realised with some wonder that I actually am a third-generation immigrant, and fall exactly within that group, since neither my father nor I speak Erse, as my Irish grandmother did when she came over after the war.

  2. says

    I fudged the dates because I was trying to estimate when Ghenghis would have come to power and reached “peak Ghenghis” – my assumptions could be wrong there. Surprisingly little is known about his personal life.

    Niall I got horribly wrong. The source I used (an article on his genetic legacy) had more uncertainty about the dates than I guess was warranted. I should multiply cross-check my references. I’ve kind of stopped doing that because it seems like most of the Internet sources from Wikipedia.

    Anyhow, I probably owe Niall and his descendants, and Ghenghis and his descendants, an apology. I.e.: a few hundred million people.

  3. says

    Yeah, if your country has a history of imperialism and/or being conquered, there’s little chance your bloodline is “pure”.

    I’m curious about some of the more remote people in the world, especially like some of the tribes in South America where they don’t like to come in contact with outsiders. It would be interesting to see if that hasn’t kept some sort of Spanish ancestry out.

  4. Pierce R. Butler says

    Marcus Ranum @ # 2: … Ghenghis … Surprisingly little is known about his personal life.

    Most historians seem to accept the “Secret History” discovered a few decades back in the Chinese archives as a legitimate translation of a document the Khan’s family put together for private use, to prevent their younger generations’ falling victim to imperial propaganda. It includes a lot of family gossip, including an account of someone presenting the most beautiful female slave they could find as a gift. The Khan found her so sexy he couldn’t control himself and “took possession” of her right then and there on the floor – then got up and ran around telling everybody in the audience chamber that they could NOT inform his mother about what they had just seen.

    FTR: Genghis Khan (and its spelling variants) means something like “Original/Legitimate Ruler”. The Khan’s given name was “Temujin”, meaning approximately “Blacksmith”, in honor of a wealthy hostage by that name held by the Khan’s father at the time of his birth.

  5. Johnny Vector says

    Or as Steve Connell and Sekou Andrews say in “The Word Begins”, “Everybody fuck until we’re all beige!”

  6. Holms says

    and then mentioned that England had, at various times, been overrun by Danes, Romans, the French, and Americans. So I asked him how he was sure that his great-great-great-grandwhatever-to-the-N’th hadn’t had a bit of a Roman holiday behind the woodpile? And, if that were the case, maybe he was part Italian. Or maybe a viking*** paused between looting and pillaging to do a bit of raping before they burned things.

    a) Those are all accepted contributors in the tapestry that is English history, therefore they are part of what makes ‘Pure English Blood’ English.
    b) They are also all white population groups, which quite possibly helps blur them all together.

    Not that I’m defending your interlocutor. The insistence that there is some sort of purity of bloodline is silly enough to begin with, and is only compounded by declaring some bloodlines better than others; but point a is the basic logic at play. Call it something of an argument from definition: some occurrences of population mixing are fine and are accepted as part of the ‘purity’ of a bloodline, others aren’t and are probably based at least in part on point b.

  7. brucegee1962 says

    Consider these two facts about the American pre-Civil War south: a) white men in the south could rape slaves with virtually no consequences, and b) any escaped slave who could pass as white, would have every incentive to do so.

    Given these two facts, the inescapable conclusion is that, if you have any ancestors at all who lived in the south, odds are overwhelmingly high that you descend from both Europe and Africa. That makes racism almost certainly an exercise in self-loathing.

    Or to put it another way — every white supremacist should be forced to read “Desiree’s Baby” by Kate Chopin to get a bit of self-realization.

  8. Kate S says

    And of course, if we’re doing “bloodlines”, John Custis was George Washington’s adopted son. His father was Martha Washington’s first husband. So genetically, this has nothing to do George Washington. Socially, it’s different. If John’s behavior towards the slave women was ignored or condoned, the family bears some responsibility.

  9. Siobhan says

    I’m supposedly 60-somethingth in line for a Swedish barony. Does that make me, like, a homeopathic Swede?

  10. says

    My last name literally means “person from this small village 20km away from where I live now”. But even the very little that I know about all those people who only passed on their genes and not names, there’s some French, Hungarian Roma, and wherever the heck my grandma’s people came from before Catherine exported them to Russia.
    Back to the person from that little village, this is a place where about everybody went through. You can’t throw a stone here without hitting Roman monuments…

  11. says

    Pierce R. Butler@#4:
    Most historians seem to accept the “Secret History” discovered a few decades back in the Chinese archives as a legitimate translation of a document the Khan’s family put together for private use

    I had not heard about that!!!! (Runs off to

    The Khan’s given name was “Temujin”

    Yup. I probably should have mentioned that in a footnote, then used the more correct form in my text. I didn’t do that because I wrote that article late and in a hurry. Thank you for the correction!

  12. says

    point a is the basic logic at play. Call it something of an argument from definition: some occurrences of population mixing are fine and are accepted as part of the ‘purity’ of a bloodline, others aren’t and are probably based at least in part on point b

    Yeah. I’ve had that explained to me similarly by a rabbi.

    My experience is that there’s a rapid back and forth flip between “race” and “culture” identity being paramount, depending on which view whoever it is is trying to defend at the moment.

    Ultimately, I suppose we’re all descendants from the 6 mitochondrial eves.

  13. says

    Yes, that’s exactly right. And very well put.

    Someone who was raped by a mongol but produced a child who could pass for (whatever) would probably tend to bury the incident, certainly over time.

  14. invivoMark says

    I like to remind white supremacists that they share common ancestry with everyone on Earth if you go back only a couple thousand years. Estimates vary, but not a lot; this 2004 study estimates 3500 years:

    Genes have been flowing constantly, and humans never lived as isolated pockets that grew and evolved independently. Racists have to ignore this fact if they want to keep believing their fantasy.

  15. Menyambal says

    I’m mostly Scots-Irish, as much as I’ve cared to check, but one day I put on a furry round hat, and dang if I didn’t look Mongol.

    My mother claims some small fraction of native-American, but it never showed. Then she got deathly ill, and I thought the hospital had sent me to the wrong room – it was an elderly Indian woman there on the bed.

  16. Pierce R. Butler says

    Holms @ # 6: … some occurrences of population mixing are fine and are accepted as part of the ‘purity’ of a bloodline…

    Which reminds me of another bit of Genghis Khaniana: fairly early in his career, Temujin suffered the embarrassment of a rival chieftain raiding his camp and stealing his wife. It took him a few years to build up his forces enough to take her back, together with the baby she’d had in the meantime. Though the kid had been born well over nine months after his mother’s abduction, he was officially the Khan’s kid and fully accepted as such, because the Khan said so.

    As things turned out, he was the most competent and loyal of all Temujin’s sons.

  17. Ice Swimmer says

    Now, people far from the places where “World History” happened might be more “pure blood”, because most of the time few conquering peoples have had any reason to go to places such as Finland. Still, at least Scandinavians, Russians and Germans (Low German merchants, German mercenaries and in the 17th century Baltic German noblemen, who the King of Sweden rewarded with manors in Finland) must have engaged in rapes and sowing of wild oats here.

    At some point Roma came here and some of them became the Finnish Kale (kale is black in Romany language), others took up farming and assimilated to the main population. I suspect that some of the assimilated may have been my ancestors (some of my relatives have, uncharacteristically for a Finn, black hair and come from the areas in the West where assimilation happened a lot). My ancestors on the whole come from Southern, Western, Southeastern, Northern and Central Finland.

  18. says

    My former father-in-law was Polish, but as he got older, he looked more and more like a Mongol. It was kind of interesting, and it didn’t bother him in the slightest.

    A lot of people experience that sort of thing – age changes or sun tan makes a big difference and suddenly: wham! Racists are incredibly un-self-aware about this issue.

    I used to hang out with a fellow back in the 80s (my cousin’s ex-boyfriend) who was relentlessly racist against hispanics.* It was bizzare how he’d go on about it, and apparently never looked in a mirror. Or, maybe, someone had thrown racist slurs at him as a kid, and he flipped over into denial about it. Because he sure looked like what he hated.

    (* Which, I guess, means against indigenous peoples from south/meso america, right?)

  19. says

    I had no idea about the african auxiliaries at Hadrian’s wall! Fascinating!

    I wonder what they thought of the weather. Fog, fog, thick fog, thin fog, and rain.

  20. says

    Also, Italiens dont always get put into the “white” category either.

    Nor the Irish. Etc.
    I almost offered the theory that, at some historical time or other, everyone has been considered inferior by someone, but I’m quite sure someone in the commentariat would point out the one case where that’s not true. ;)

  21. Tsu Dho Nimh says

    Blood group types, which were all we had until DNA analysis got cheap and easy, show a streak of blood types most commonly found in Asian populations running out of the steppes, across Hungary and ending up in Austria.

    I can claim European, Native American and African ancestors. Don’t know about the Chinese and other Asians. And I look really, really average white person. It’s more like “CDA” (Caucasian of Dubious Ancestry)

  22. Ice Swimmer says

    Marcus Ranum @ 22

    Does homeopathy also work with titles of nobility and is her rank now friherrinna^60 (and will that bring her higher than a grevinna)?

  23. kestrel says

    I thought the joke was funny and so did the Partner. :-)

    I raise livestock. There is always someone going on about “pure blood” etc. and TBH I do raise registered stock. However I don’t kid myself; I know very well “things happen”. There is the story of the Morgan horse; one of the big breeders decided to put in a little American Saddlebred, fudged the papers, and started winning big in the ring. That was great so he did a bit more fudging. Soon everyone wanted his horses and before you knew it, there was so much American Saddlebred in the Morgan breed there was nothing to be done and no going back. And where do Morgans come from in the first place? From one prepotent stallion bred to any mare they could find. How on earth was that “pure bred” to start with? Yes… I know. Certain characteristics were selected for etc. My point is, all you have to do is go back far enough and you find Chop Suey horses or humans or whatever. I always thought that was complete idiocy to talk about Pure Blood.