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What Is An Endogamous Marriage?
Updated on December 21, 2022
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What Is An Endogamous Marriage?

Endogamy is the practice of marrying within the same group. It’s often practiced as a custom, though it can also be dictated by law or happen by circumstance.

Some examples of endogamy include marrying within the family, clan, tribe, and caste—or the same social, cultural, religious, or ethnic group.

Old Order Amish, Orthodox Jews, Cajuns, Polynesians, French Canadians, the Parsi of India, the Yazidi, and Armenian-Iranians are endogamous societies.1,2

Endogamy is not the same as incest, which is considered illegal and defined as sexual relations between close blood relatives.3

However, endogamy—like incest—increases the risk of genetic disorders.

What Is An Endogamous Marriage? 2

Why Do People Practice Endogamy?

Endogamy is a common practice in many cultures. It can be done as part of a custom (such as religious tradition), or it can be dictated by law.

By practicing marriage within a specific group, the group can isolate and preserve itself.

It is a form of segregation that prevents one group from merging with other groups that do not share the same culture, beliefs, practices, or resources.4

Some families engage in endogamy to retain their property, wealth, or social class.5

Endogamy also helps one’s social group survive by promoting unity and giving them better control over the resources they need to thrive.3

This is why endogamy is common in displaced populations—such as migrants and refugees—who live in places away from their geographic origin.

In other cases, people get into endogamy because they don’t have much of a choice. A good example is living somewhere isolated, like an island (geographical isolation).

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Endogamy & Genetic Disorders

Since endogamy isolates one’s group, it results in a small gene pool. Endogamy increases the risk of genetic disease.4

The following conditions are commonly seen in endogamous communities: 

  • Stillbirths and increased risk of abortions
  • Perinatal mortality
  • Congenital malformations
  • Autosomal recessive disorders

The genetic diseases that affect endogamous groups tend to vary. For example, Bloom syndrome is a rare condition that is common in Ashkenazi Jews.

Unfortunately, this increased risk for certain diseases can lead to a group’s extinction.

How Endogamy Affects Genetic Matching & Ancestral Research

One of the effects of endogamy is the risk of genetic diseases. But aside from that, there is another aspect to consider. 

Marrying within your group boundaries can make genealogical research either easier or more complicated. It depends on the circumstances.

Genetic matching is usually more difficult for people without endogamous relationships in their families. They have to find eight sets of great-grandparents.

People who have endogamy in their families have it easier. They only need to locate fewer grandparents to confirm a genetic match. 

It’s because the same couple will appear on multiple lines of their genealogy results.

Additionally, it’s easier to trace your family history when relationships are more insular.

For example, if your family was Acadian Catholic (an endogamous group), you can easily learn more about your heritage.

If you’re descended from religious groups who practiced endogamy and attended the same church, church records may be enough to identify your whole family.

It would be a different story if your ancestors practiced a religion that didn’t keep records. In these cases, endogamy has no effect on your research.

Without detailed record-keeping, it isn’t easy to make distinctions since the DNA matches tend to overlap with one another.

For example, let’s say your aunt on your mother’s side married your uncle on your father’s side. This creates a double-cousin scenario in your family tree.

Not only do you share DNA with your cousin because her mother is your mother’s sister. You’ll also share DNA with your father’s side because her father is your father’s brother. 

You are maternal and paternal first cousins, which means you share twice the amount of DNA shared by first cousins.

Endogamy & Genealogical Relationships

In a standard DNA test, the company to which you send your sample will not know that your family practiced endogamy.

This is because endogamous populations cannot be easily distinguished.

A double first cousin would look like a half-sibling on paper. He/she will have about the same amount of DNA you’d share with the same mother or father. 

It’s even more complicated when this relationship is further back in your family tree and happened with your grandparents or great-grandparents.

And because endogamy rarely only occurs once in a family, most people end up sharing a lot more DNA with their cousins than is expected.

When marrying within a specific group, it can be challenging to determine genealogical relationships.

DNA overlaps in your community, not because of one recent common ancestor but because you share multiple distant relatives in common.

Identifying Endogamous Relationships In DNA Results

One of the best ways to spot an endogamous relationship is to look at the DNA size and total amount of DNA you share.

Most DNA tests provide this information. You can examine the number of shared DNA segments and identify the largest DNA segment and its length.

If this seems complicated, your best bet is to take your DNA test results to a geneticist who can help you make sense of what you are looking at. 

A geneticist will assess your genetics and provide information on your genealogy. They also offer services where that can help you analyze your genetics on your own.

It’s also important to consider the geographic location. Knowing where your ancestors lived may help rule out some groups. 

A thorough genetic study, paired with efficient statistical analysis of available data, may be needed in some cases.

This is especially true for extended families with very limited information.

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Updated on December 21, 2022
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5 sources cited
Updated on December 21, 2022
  1. Endogamy.” International Society of Genetic Genealogy Wiki.
  2. Endogamy.” Bionity Life Science Encyclopedia. 
  3. Incest.” Legal Information Institute, Cornell Law School.
  4. Endogamy: Definition & Overview.” Intro to Anthropology,
  5. Endogamy and Social Class in History: An Overview.” Internationaal Instituut voor Sociale Geschiedenis, Cambridge.
Kelly Jamrozy
Kelly Jamrozy
Content Contributor
Kelly has experience working with clients in a variety of industries, including legal, medical, marketing, and travel. Her goal is to share important information that people can use to make decisions about their health and the health of their loved ones. From choosing the best treatment programs to improving dental and vision health to finding the best method for helping anyone who is struggling with health issues, she hopes to share what she learns through informative content.
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