40. Endogamy and Genealogy

 

What a great word!  It rhymes with “bigamy” and “polygamy”.  Broadly defined, endogamy is the practice of marrying within a specific social group, religious denomination, caste, or ethnic group.  Endogamy is common in many cultures and ethnic groups around the world.  Endogamy may result in transmission of genetic disorders within the relatively closed community.

 

Endogamic marriage patterns may increase the frequency of cousin marriages in a population, and may cause high probability of children of first, second, third cousins, etc.

 

In DNA, endogamy commonly refers to any cousin marriage that affects a family tree.  And we know that cousin marriages do occur so, be on the lookout. 

 

If cousin marriage has occurred in a family tree it is referred to as pedigree collapse.  You are reducing the number of ancestors in the tree since some of them are common to the marriage partners.  It creates stronger DNA matches (i.e., a higher centimorgan count) between the DNA matches than otherwise might be expected.   Your investigation might confuse a second cousin with a third cousin for example, simply because the centimorgan level is higher.

 

And you thought you knew the relative values of centimorgans for various levels of cousins.  Researcher beware of the potential for endogamy impact.  It just might explain some otherwise confusing numbers.  And remember, a centimorgan is only a measure of statistical probability.  It is not a unit of measurement (like a gallon or an inch).  You have to love the odd things that you learn in the world of genealogy.  

 

 

 

Ron Gilmore

Email:           rvg3@me.com

Website:       https://www.rgenealogy.ca