Marriage between cousins

When a young neighbor learned her father and mother were first cousins her reaction was an instant “Ewww.”  She was embarrassed to think her parents were so closely related.  

But genealogists know that cousin marriages occur in all family trees, and the further back you go, the more likely you are to find cousin marriages of one degree or another.  In part this was due to a limited pool of possible mates in small settlements in Europe and this country.  

It wasn’t so long ago that marriages between first cousins were illegal in most states.  The rationale behind the law was that the children of first cousin marriages would be either mentally or physically defective.  The prohibition between first cousin marriages had been around a long time. In the Middle Ages the Catholic Church forbade cousin marriages to the fourth degree.  Other religions, including Protestantism, didn’t impose restrictions.  In fact, some religions actively encouraged cousin marriages and even uncle-niece marriages to keep property in the family and their children in the religion.  Many royal families married their cousins routinely, and in ancient Egypt dynasties favored brother-sister marriages.

Modern genetic research has proven that cousin-cousin marriages are fine and there is no danger in these marriages of children having problems — with one great caveat:  If there is a hereditary disease in your family, it would be wise to have genetic tests done to be sure the parents aren’t carriers.  Some diseases and inherited conditions run in families and others can skip generations, only to appear seemingly out of the blue.  Would-be parents who are closely related who know they are carrying a genetic risk often choose not to have children but to adopt instead.

Among the genetic conditions that can occur in families are Huntington’s disease, early onset dementia, hemophilia and breast cancer, to name only a few.  Queen Victoria’s legacy of hemophilia caused the deaths of many of her descendants and can be said to have been a factor in the Russian Revolution and the end of the tsars.

The marriage of double first cousins can make it easier for a disease bearing gene to surface.  What are double first cousins?  Double first cousins occur when a marrying couple are first cousins and are the children of either two brothers marrying two sisters or a brother and sister marrying a sister and brother.  Clearly in that case the children get a double dose of certain genes.  That would ramp up the risks of inheriting any recessive gene carrying a disease.   Still, family trees often have double-cousin marriages with perfectly normal children.  Sometimes it’s as if a game of genetic roulette is at play in all our families.

If you have any risk factors in your tree you might want to undergo genetic testing prior to having children and discuss it with a doctor.  In many cases all that is warranted is careful monitoring.  In others, it’s more serious.  But when you encounter a cousin-cousin marriage in your tree, don’t go “Eww”; it was actually very common.

Columnist Nancy Battick of Dover-Foxcroft has researched genealogy for over 30 years. She is past president of the Maine Genealogical Society. Reader emails are welcome at nbattick@roadrunner.com. Her semimonthly column is sponsored by the Aroostook County Genealogical Society which meets the fourth Monday of the month except in July and December at the Caribou Library at 6:30 p.m. Guests are always welcome. FMI contact Edwin “J” Bullard at 492-5501.

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