Common family tree problems. Three terms simplified.


Incest? Endogamy? Pedigree Collapse? What even is that?! Family Tree Problems briefly explained.

(These are just some of the inevitable things genealogists uncover, and today we are going to distinguish between these three terms.)

An example of a basic three-generation family chart. 

Incest occurs when close family members have a romantic relationship. That could be brother and sister, father and daughter, mother and son, or grandparent and grandchild. Below is an example of how this can show up in some family trees.

An example of Incest in three-generation family chart. 

Endogamy is defined as the tradition of marrying only within the boundaries of a local “community, clan, or tribe”. It is also a term used to define cousins marrying cousins. This practice was used as a form of resistance against integration with “outsiders.” There was a time that this was an acceptable custom in many cultures and ethnic groups around the world. Today, we now know that such practice may lead to an increase in genetic diseases and in extreme cases possible group extinction. To determine whether your family tree is endogamous, the practice would have to be continuous throughout many generations.

An example of Endogamy in six-generation family chart. 

Pedigree Collapse, a term used by genealogists to describe one or few isolated incidents of people in family trees that share an ancestor and marry each other. Whether intentionally or not, this event causes a “collapse” on the family tree. An example would be 1st or 2nd cousins marrying each other as they would share the same grandparent or great grandparent. 

An example of a Pedigree Collapse in four-generation family chart. 

In short: Incest occurs when close family members have a romantic relationship and shows up in your family tree when they have children. Endogamy happens when cousins marry cousins repeatedly over many generations. A Pedigree Collapse occurs in your family tree when two people marry and share the same ancestor which can at times be an isolated event or occur a few times. |

Side Note: There are many endogamous populations around the world. So, if you’ve taken a DNA test and believe you come from an endogamous population, it is possible to have a “false match.” I will explain all about this in my next blog post!!! 

( All ancestor chart examples were made by Jasmin Kateri using tools in the program MacFamilyTree 9. )

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