A Study of Consanguinity in Modern European History

How distantly are people related?

Readership: All; Those interested in tracing European ancestry;
Author’s Note: This topic was requested by a reader, Julia Mykaele.
Length: 2,640 words;
Reading Time: 10 minutes;


Consanguinity describes the close relationship between two people who are descended from a common ancestor, and this usually implies a sexual and/or marital union.  A near synonym would be kinship, which distinguishes blood-relation from affinity.

In November 2019, this research article was published in Science.

J. F. Schulz, D. Bahrami-Rad, J. P. Beauchamp, J. Henrich, “The Church, intensive kinship, and global psychological variation”, Science Vol. 366, Issue 6466, eaau5141 (2019 November 8).

Since its publication, this article has seen an explosion of reviews on MGM, including the following.

All these news sources have a Leftist bent, especially NPR.

Here’s a summary excerpt from the NPR article.

He and his team looked at the records in the Vatican’s archives and found that over the centuries, the Church kept widening the circle of relatives that one wasn’t allowed to marry. “By early second millennium, they’ve extended it out to sixth cousins,” he says.

The bans didn’t just include blood relatives — they also included relatives by marriage and spiritual relatives, he adds. There are also bans on adoption and remarriage.

“If you eliminate adoption and remarriage, you prevent lineages from getting heirs and lineages literally die out,” he says.

I’m no historian, but I can believe this really did happen – officially, that is.

The researchers don’t know the precise motivations behind these bans, but they think the limitations had a dramatic impact on how society was organized.

That restructuring of societies in Western Europe in turn also benefited the church, notes Henrich.

“In some sense, the church is killing off clans, and they’re often getting the lands in wealth,” he says. “So this is enriching the church. Meanwhile, Europeans are broken down into monogamous, nuclear families and they can’t re-create the complex kinship structures that we [still] see elsewhere in the world.”

The authors offer the argument that marrying farther outside your gene pool is better for enhancing the “virtues” of individualism, democracy, and culture.  Taken further, this could argue for the support of interracial marriages as well (AKA miscegenation)*.

How prevalent is consanguinity in history?

After thinking about consanguinity for a while, I began to wonder, just how much consanguinity has occurred throughout history?  I’m certain there’s no hard data on this, so instead, I made a mathematical model that estimated the number of one’s ancestors that would be alive at any time in history. 

Of course, this model is purely theoretical, but it should give us a ballpark idea of how many ancestors would have to be alive for each generation if we required perfect non-consanguinity.

The model is based on the following presumptions.

  • Each person has exactly two parents (of course).
  • The age of reproduction is chosen to be 25 years old, which is probably close to the average.
  • Each mating event occurs with absolutely zero consanguinity to any degree.

Based on these presumptions, we can form a parametric equation to relate the date to the number of generational cohorts alive at that time.  This equation is 25n = 2n, where n is the generational iteration along one’s genealogical ancestry.  This equation generates the data listed in the following table.

I also compared this data to the world population estimates by year, which is also shown in the same table.

We can see that the number of ancestors within each generational cohort increases exponentially.  As a result, the number of ancestral generational cohorts goes up by an order of magnitude every century.

Before I constructed this model, I had guessed that the number of cohorts might diverge about 2 to 3 millennia ago.  But it blows up within a much shorter time span than I expected.  The number surpassed the world population within just 700 years!

Of course, we know that can’t happen in reality, so consanguinity must be occurring much sooner than 700 years ago, and not back in antiquity, as I had originally thought.

Cleo de Merode, dancer, beloved of Leopold II of Belgium. Born 27.9.1875 Paris, Died 17.10.1966 Paris. Portrait shot, 1902 (Nadar). Digitally colored.

A Study of My Own Ancestry

After seeing the surprising data generated from the model above, I decided to study some ancestral records carefully, to see whether consanguinity had occurred, how frequently, and to what degree.

My father had already put together a family tree based on interviews he had with his grandparents and two of his great aunts.  So I had quite a lot of information about my ancestors back to my great-great grandparents (n = 4).  But this information only took me as far back as the early-to-mid-19th century.  I had nothing before that.

So I took what data I had, and used it to kick start a more exhaustive study of my pedigree on Ancestry.com.  Even after spending more than 50 hours combing through census records and many other documents, I could only trace my ancestors back an additional century or so.  The problems I encountered were as follows.

  • Some of the ancestral information my dad had gathered from word of mouth through his ancestors did not match the records.**  Yet, other information in the records matched so accurately, that I knew it was the same person.  From this I learned that older people don’t tell their children and grandchildren all the gritty details about everything that happened when they were younger.
  • Every new lead brought one or two more names to research.
  • With so many names, it was hard to decide which lead (which branch) to pursue next.
  • Many leads turned out to be dead ends (no information available).
  • I spent most of my time comparing notes between possibilities, searching for some confirmation to verify the connecting relationship in question, just to be sure it was true/accurate.
  • I eventually traced my ancestry back to people who were not born in the United States.  At that point, if I wanted to go further, then I would have had to procure documents from Ireland and Germany, and pay a foreign professional (e.g. a bilingual genealogist/historian) to do the leg work of searching and sifting through the records. I’m not independently wealthy, so for a while, I felt like this was going to be the end of the search for me.
Maude Fealy (1881-1971), American actress, by Lizzie Caswall Smith, circa 1900-1910.

In summary, as you go farther back in time, it becomes more difficult to find information, and there is more uncertainty surrounding that information. 

But as I continued to review all the ancestors I had studied, which by that point included more than 400 individuals, each with their own life stories, I stumbled across one connection to a family tree that had already been researched and developed – with some branches going all the way back to the late 15th century!  (ca. 1480 AD)  Apparently, I have a wealthy third or fourth cousin who had already paid a genealogist in Germany to research our ancestry.  In addition, the ancestral branch that we shared had been very wealthy in medieval times, therefore many records for their major life events had been well maintained and well preserved.

Studying your genealogy is fascinating!  Once you get back before the early 18th century, the names grow more grandiloquently bizarre. I found monikers like Achilles, Balthazar, Melcior, (males) and Drusilla, Gunakunda, Vinelda, (females), just to name a few.  Perhaps it’s just as interesting to see how familiar names have morphed into their modern equivalents, like Heinreich → Henry, Yachov → Jacob; Johann → John; Vilhelm → William; Others, like Peter, Michael, Elisabeth, and Margaret have never changed.  It’s amazing how many ancient Hebrew names have stood popular throughout time.

Also, if you take the time to piece together any one person’s life story, it’s truly amazing – and shocking.  Keep reading for more on this.

Alexander Dumas

Consanguinity Within My Own Pedigree!?!

Back to the topic of consanguinity.

After studying this branch for a while, I found not one, but several married couples who lived in the 18th and early 19th centuries who shared a common ancestor living in the 16th or 17th century.  But it wasn’t quite as simple as a linear descent.  For example, one couple in generation 9 shared one set of great-great-grandparents in generation 13, which means that the total number of great-great-grandparents between the two of them was 30 instead of 32

It gets more complicated.  The two parents of the wife in generation 9 shared two different sets of great-great-grandparents in generation 14, along different branches of the family tree, which means that the total number of great-great-great-grandparents between the couple in generation 9 was 60 instead of 64.

The nearest consanguinity in degree that I was able to find was a couple who shared the same great-great-grandparents (Δn = 4).  According to the records, it was very difficult for this particular woman to produce children.  During her lifetime, she had 2 children that grew to adulthood and reproduced, but she had two more that died within the first year of birth, and 4 miscarriages.

There wasn’t enough data to be certain, but I couldn’t help but wonder if the repetitive consanguinity from generation to generation contributed to her impaired fecundity.

At first, this discovery shocked the $ћ!t out of me, because I thought it meant I had inbreeding in my ancestry.  But then I realized that because of the bottleneck effect, my ancestry couldn’t be much different from anyone else’s, anywhere in the world.  Now, I believe this is natural and common.  We’re all descended from Adam and Noah.  Everyone is inbred to some degree.  My father told me that once he calculated that everyone in the world is no more distantly related than 53rd cousins.  Based on the model I described earlier, I would say that number is too high.

So what’s “normal”?

Anyway, based on this example, you can see how the number of generational cohorts expands exponentially for the first five generations.  But then over the course of the 5th to 9th generations, some degree of consanguinity occurs, eventually leading to a bottleneck effect in the total number of ancestral cohorts during the 12th to 14th generations.  If you trace your ancestry back 16 generations (~ 400 years), you should find a total of 65,536 unique ancestors.  If you find any fewer than this, then there’s been some consanguineous shenanigans.

I imagine that these people never guessed that they were so closely related as they were.  Think about it, how would you ever know whether the 256 (or so) people living 200 years ago whom you are descended from never once had any sexual relations with the 256 (or so) people living 200 years ago whom your spouse is descended from?  This much is unknown, but we do have a large collection of popular lore which recounts stories of medieval peasants hopping from hole to hole like bunnies in a meadow.  Sure, consanguinity was frowned on by the culture, and forbidden by the Catholic church, but promiscuity is as old as humanity, and they didn’t have the certainty of DNA testing.

Cain flying before Jehovah’s Curse, by Fernand Cormon (1880)

Social Environment Factors

There are some factors related to the social environment of early modern Europe to consider as well.

  • People living during this time period didn’t travel like we do today.  Outside of military excursions for males, 90+% of the people were born, lived, died, and were buried in the same town, and this went on for centuries.  I could believe that within just 200 years, everyone in a relatively large medieval town of 10,000 to 20,000 was no farther apart than 3rd or 4th cousin.  (For example, Wittenberg had a population of nearly 5,000 during Luther’s time.)
  • Also, people tended to marry within their race and social class much more rigorously than we do today.  This was especially pronounced for the ruling class.  This produced an increased likelihood of consanguineous unions.
  • Last but not least, we know that 100% of married couples were completely chaste, 100% of their lives!  <<<sarcasm>>>  Imagine how that tangles up the banyan tree even more.  Here’s another good reason why it should be called “branch swinging”.

All of the above conditions increase the probability and frequency of consanguineous partnerships.

The View of the Zwolle, by Hendrick Ten Oever (1675)


We have the notion that a family tree is linear and two dimensional.  But in reality, a family tree is more like a tangled mass of hundreds of coathangers.

It’s true that the Catholic Church forbade consanguineous marriage within two degrees of separation. However, this was rarely enforced.  The truth is that there were many people of all classes who married third or fourth cousins for various reasons.  Most noteworthy of all is the sheer ignorance about precisely whom is included among one’s kin relations.  In addition, we can safely assume that there were many individuals who were borne of an illicit union, one which was never mentioned above a whisper, much less went into the official genealogy books.

In light of the above considerations, I’ll conclude that the “scientific” authors’ claim that the taboo of consanguinity (which was presumed to have been enforced by the Catholic Church) “created” western individualism is all conjecture.  I can believe that certain direct lineages died out, but I’m not sure about whole tribal and clan identities, except in the case of a genocidal war.  However, I could easily believe that individualism is a heritable trait common to all Western Caucasians.  I suspect that all the hype over the taboo of consanguinity is merely a cover story intended to displace any arguments of heritability.

Ava Gardner (1944)


* On a side note, I don’t believe there is any moral compunction for marrying outside one’s race.  Several noteworthy figures in the Bible had interracial marriages, including Moses, Salmon, Boaz, and Solomon, some for better, others for worse.

However, in Jeremiah, God reprimanded the Israelis for taking foreign wives.  There were several reasons for this.

  • The men were divorcing their wives and abandoning their families for younger and presumably more attractive foreign wives.
  • The men were being led astray into idolatry through the influence of their foreign wives.
  • Interracial marriage en masse contributes to the weakening of familial bonding and lineage.

We also know how things ended for Solomon, as a result of being influenced by his foreign, pagan wives.

** For example, my great-grandfather (GGF) told my father that he and his younger sister had grown up in an orphanage since he was six.  So they had always believed that their parents had died, and this was the story that everyone in my family believed.  But after poking around on Ancestry.com, I found other census records showing that my GGF’s mother lived a full 20 years after my GGF went to the orphanage, and that his younger sister was born six years after his father had died.  Apparently, once his father (my GGGF) kicked the bucket, his wife sold the farm, dumped the children at an orphanage, and skipped town to live a life of hedonism and harlotry.  Even if anyone in my family did know the truth, it’s obvious why they would not pass this information on to their progeny.

If any of my readers care to go digging around in their own family tree, I guarantee that you will eventually find sordid tales of sin and shame which your good old grandpappy would never pass down to you by word of mouth.



About Jack

Jack is a world traveling artist, skilled in trading ideas and information, none of which are considered too holy, too nerdy, nor too profane to hijack and twist into useful fashion. Sigma Frame Mindsets and methods for building and maintaining a masculine Frame
This entry was posted in Consanguinity, Genealogy, Racial Relations, Self-Concept, Statistics Reports. Bookmark the permalink.

12 Responses to A Study of Consanguinity in Modern European History

  1. AngloSaxon says:

    What on earth is the first picture? An abomination which causes revulsion?


    • Jack says:

      @ AngloSaxon,
      It’s a picture representing the liberal argument for interracial couples. I don’t believe there is anything wrong with interracial couples from an individual standpoint (as I mentioned in the footnote), but it’s wrong to press it forward as a societal norm as the liberal media does.


      • AngloSaxon says:

        Yeah if everyone does it then there won’t be distinct tribes and nations anymore, just one big horrifying blob.


      • Novaseeker says:

        Most likely is not a scenario where “everyone” is interracial offspring, but rather one like Latin America, where there is a small group of very lightly to no interracial “white Spanish” elite ruling class in politics, business and cultural life, and then the mass of mixed browns as the rank and file below them. All the Latin countries are like this except for Brazil (where there are some racially mixed elites, but also quite a few who are not, especially among immigrant groups … see, e.g., Gisele Bundchen), and Argentina/Uruguay (smaller native populations, and they were killed/marginalized in a way similar to North America (Argentina and Uruguay are about as “white” as Idaho). If you want a preview of what is coming in the US, look to Latin America, and you’ll have a fairly good idea of what is coming to the urban/metro US … the rural areas will remain almost entirely white, likely, but with decreasing population trends as we have already seen.

        Liked by 2 people

  2. ramman3000 says:

    I am very interested in this topic. I will try to contain my enthusiasm (but not really).

    Consider this study on inbreeding. The inbreeding coefficient is the percentage of genes that two people share in common. The inbreeding coefficient varies from double first cousins (0.125) to second cousins (0.0156). They noted:

    “In general, consanguinity does not increase the risk for autosomal dominant conditions in offspring when one of the parents is affected, nor for X-linked recessive conditions if neither parent is affected (Hamamy et al. 2007b). [..] If there is no known genetic disorder in the family, first cousin marriages are generally given a risk for birth defects in the offspring that is double the population risk (Stoltenberg et al. 1997) (for example, instead of 2.5%, it becomes 5%), or the risk may be given as 1.7–2.8% higher than the population background risk, mostly attributable to autosomal recessive diseases (Bennett et al. 1999, 2002; Tadmouri et al. 2009; Zlotogora and Shalev 2010).”

    So the risk of standard first-cousin marriage is non-zero, but it rarely outweighs the perceived social benefits: it is usually worth the risk. Countries that practice cousin-marriage are not drowning in birth defects.

    As an Anabaptist with deep Mennonite ancestry, I was amused to find instances of cousin marriage (i.e. having the same ancestors on multiple branches of the tree). But this is not unusual. For example, according to some experts, nearly everyone of European decent is descended from royalty. Indeed:

    “80 percent of England’s present population descends from Edward III [..] Among his documented descendants are presidents (George Washington, Thomas Jefferson, John Quincy Adams, Zachary Taylor, both Roosevelts), authors (Jane Austen, Lord Byron, Alfred Lord Tennyson, Elizabeth Barrett Browning), generals (Robert E. Lee), scientists (Charles Darwin) and actors (Humphrey Bogart, Audrey Hepburn, Brooke Shields).”

    In a previous post, Nikolai Vladivostok said:

    “Further, children of parents with similar genes will have weaker immune systems. This effect will probably compound over generations.”

    But this is wrong. Due to the effects of natural and artificial selection, this compounding can occur in both directions.

    From the middle ages to the industrial revolution, child mortality was very high. The poor genetic stock died and a relatively small group of the fittest out-bred everyone else. That is why so many people are descended from Edward III. During this time, the overall population mutational load improved due to inbreeding. But then child mortality was conquered in the modern era. And so began the falling of general intelligence and the increasing of population mutational load through dysgenic breeding. For centuries in European populations, inbreeding has led to better genetic stock while more diverse breeding led to declines.

    The problem of producing genetic mutants is a short-term problem. The long-term problem is if those genetic mutants survive long enough to reproduce. Hundreds of years ago, genetic mutants would have died young, far before they could reproduce. But in modern times, they survive and reproduce in very large numbers. Cousin marriage is actually better than random marriage if the genetic stock of the cousins is better than the random pairing.

    Liked by 3 people

    • ramman3000 says:

      It’s worth noting that a cousin-marriage is riskier by about the same amount as having a child at 40 vs 21 is. In other words, in the U.S. where having children is often delayed by a decade, we get most of the negatives of increased birth defects with none of the potential social benefits of cousin marriage with its younger age of births.

      Liked by 1 person

    • Every breed of animal and vegetable that we have today comes from inbreeding. Oftentimes very close inbreeding. This if course can create problems, which those older and wiser than us moderns would cull, or at least neuter, before they could pass on those problems. Nowadays this is not done – it’s considered cruel, after all – and a big part of why we have troubles with animals like deformed bulldogs and aggressive pit-bulls (which were originally bred to NEVER attack humans, and were used as nanny dogs when not fighting other animals). To think the same thing would not apply to humans is foolish. (I’m sure there are a few SF/F books out there where humans are bred thusly (almost certainly by the Bad Guy(s)), but I’ve never read them.)

      Liked by 1 person

  3. Elspeth says:

    As an American descendant of slaves, whose family is all shades of brown from cafe au lait to dark chocolate, and whose husband’s verifiable lineage contains three ethnicities (as recently as his white great-grandfather and half Cherokee grandmother), I find myself ambivalent on this topic.

    Americans of all hues are, by and large, mutts.

    Liked by 2 people

  4. Ed Hurst says:

    Centralized governments hate strong tribes, and strong tribes hate centralized governments. A certain amount of the official story you cited is true for the obvious reasons, but you correctly note that lefty theories about such things tend to leave the ground of solid good sense. And lefties generally prefer centralized governments over strong tribes, so there is an underlying motive.

    Liked by 3 people

    • Jack says:

      “Centralized governments hate strong tribes, and strong tribes hate centralized governments.”

      The Catholic Church (as a historical entity) functioned much like a centralized government. Similar to governments, could the Catholic Church have also shared the same antipathy to strong tribes? Is there any evidence of this? Maybe the Catholic Church imposed these regulations as a long term strategy to gain more power over society, and especially over the ruling classes.

      “…lefties generally prefer centralized governments over strong tribes, so there is an underlying motive.”

      It seems reasonable to assume that lefties (and their accompanying liberal mindset) are descendants of those who had no tribe, or who were rejected or somehow excluded from the tribe. Thus, their desire to implement a socialist government could be interpreted as an attempt to form a surrogate tribe for the purpose of reintegrating themselves within society. If true, then this would mean that liberalism is a generational curse.


      • Ed Hurst says:

        I can’t give you any footnotes, but the Medieval leadership of the Church had developed up a strong antipathy for the independence of regional rulers. We might as well say that was the birth of our first consciously organized wannabe one-world government.

        Liked by 2 people

  5. Pingback: Is the Pendulum Effect caused by Western Individualism? | Σ Frame

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