Where’s Your Endogamy? Survey Says….

Sunny Morton

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Where are people finding endogamy on their family trees? We report results of a survey of genetic genealogists who have endogamous roots.

Many people don’t realize their family tree is affected by endogamy. Endogamy is when members of a small community intermarry repeatedly over many generations. It’s common for places that are geographically isolated (think mountains and islands) or culturally insular (like some religions that discourage marriage outside the faith).

How do I know if there’s endogamy on my family tree?

There are several ways to figure out whether you’ve got endogamy in your family history. We’ll share some DNA strategies below. 

Additionally, it helps to be aware of what places and people have been most affected by endogamy. As you learn your family history, you can research their communities to see if they were isolated and therefore prone to a lot of intermarriage. 

Where can endogamy be found?

We can list a bunch of commonly-given answers. but I thought I’d share the results of a recent poll of those who have taken our Endogamy & DNA Course. We asked them what endogamous communities THEIR ancestors were part of.

This was a casual self-reported survey with 130 responses (29% response rate). It’s not the kind of thing we’d publish in a scientific journal. But it illustrates the many kinds of communities people may not even have considered as being affected by endogamy. 

Here’s what they said:

“Small-town U.S.A” is actually the top individual answer. Does that surprise you? Maybe not, if you’re aware of all the isolated communities in the U.S., well into the 1900s. More specific U.S. places reported in this survey include Appalachian mountain dwellers, Virginia, German settlers in Louisiana and Pennsylvania, the Carolinas, Hawaii, Ohio, New Mexico, Long Island and more. Time periods reported include the colonial era (including Mayflower ancestry and other founder effect populations) and the 1800s.

The next-largest response is for Jewish admixture. This is already well-known among researchers. We didn’t ask about the many possible sub-categories for Jewish groups from around the world: Ashkenazi, Sephardic, Mizrahi, Ethiopian and others. One of our respondents specifically mentioned descent from Iraqi Jews.

The “Other” category, which was the most frequent response, breaks down pretty quickly into lots of places and people from around the globe:

  • Several people reported Ireland, French Canada, Sweden, Finland and Portugal.
  • As a group, island and coastal populations show up frequently: the Azores and Madeira, Sicily, coastal Scotland, Bahamas, Hawaii, Philippines and Croatian islands/Dalmatian coast. 
  • Other Canadian regions mentioned are New Brunswick Loyalists, Nova Scotia, the maritime provinces, and Ontario.
  • Cultural groups that were self-reported include: Roma, Germans from Russia, Mennonite, Amish and Mormon (Latter-day Saint).
  • Respondents also mentioned South Africa, Scotland, Wales, England, Spain, Italy, Germany, Bavaria, Ecuador, Mexico and Indigenous (unspecified).

How does endogamy affect my family tree?

You may be already deep into your family research by the time you realize you’re working with endogamous communities. Don’t get discouraged! But do be aware of additional challenges you may face and strategies you may need.

The effects of having many ancestors from different branches of your tree who were related to EACH OTHER can complicate genealogy research. The same can be said for the effects of endogamy on your DNA match list, both because your individual matches share more DNA than they should with you, given your actual genealogical relationship, and because your matches all seem to be related to each other instead of neatly dividing into separate branches of your family tree.

As far as the genealogy goes, keep working on it! DO GENEALOGY is always a next-step answer in genetic genealogy, and especially when the tree is complicated. For some times and places that don’t have great records available, this is challenging. In the United States, one strategy (especially good for the South) is to consult land records. Not only can land records be strong genealogical resources, but they can help place potential parents within a close enough proximity to show they could have met and produced a child.

Let’s bring this discussion back to DNA. The degree to which your DNA match list may be affected by the endogamous patterns of your ancestors may depend on several factors, such as: how intense the endogamy was; how long ago the intermarriages stopped; your unique inheritance pattern; and how many lines on your tree were involved.

The effects of endogamy begin to show up, for many people, when they start working with their autosomal DNA matches, says Diahan Southard. “They start dividing their matches into genetic networks–and it simply doesn’t work. The matches all seem to be related to each other, or there aren’t enough networks to represent each branch of their family tree. They think it’s their fault. But it’s not!” 

What DNA strategies can you use? First, it’s possible your family lived in an endogamous community, but that, over time and with generations of distance, the effects have “worn off” and don’t show up in your DNA match list now. Try sorting your DNA matches using the strategies demonstrated by Diahan Southard using the Ancestry “dot” method or MyHeritage labels or use MyHeritage’s AutoClusters tool. (If you tested elsewhere, sort your matches using the Leeds Method). If your matches don’t sort into distinct groups, you may have endogamy.

If you can see the effects of endogamy on your autosomal DNA matches, we recommend you take our unique Endogamy & DNA Course. Our course gives you straightforward strategies for reviewing your match list at each of the testing companies that offer different analysis tools. It helps you sort out (and adjust for) similar-looking situations like multiple relationships or pedigree collapse.

Ready to learn more? Watch this quick video tutorial on endogamy, multiple relationships and pedigree collapse:


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1 Comment

  1. Jorge L Camuñas

    Although you did not mention it specifically, there is a lot of endogamy in Puerto Rico. I guess we fall under the groupings of closed societies, small towns and island nations. I must sign up for your course!


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