Cousin marriages

By Nancy Battick

The idea of cousins marrying each other triggers the “ick” factor in many people or a rehashing of redneck jokes involving bride hunting at family reunions. The truth is that cousin marriages have been common in the past. 

For example, royal families have been marrying their cousins for centuries, mainly because a royal groom was only permitted to marry a royal bride and the supply wasn’t endless. The ancient Egyptian pharaohs married their full or half-sisters.

Uncle-and-niece marriages also happened in many dynasties. Cousin marriages were common among the aristocracy where only other aristocrats could be considered as potential partners. 

In colonial times here in the U.S., the pool of eligible partners was limited, meaning that cousin marriages occurred. Cousin marriages also happened and still do happen in certain religious communities where a partner has to belong to the religious group for the marriage to be valid.

Today, however, we look askance because we now know about DNA and the possible genetic consequences of close relative marriages. Some serious diseases such as hemophilia are genetically linked. 

Hemophilia is passed from mothers to their offspring, as in the most famous case of the young heir to the Russian throne, Alexis, who died in 1918. His mother, Empress Alexandra, passed the gene she inherited from her mother, a British princess, who almost certainly inherited the gene from her own mother, Queen Victoria. Other of Victoria’s descendants carried and passed on the gene as well. 

The last information I can locate indicates that 25 U.S. states forbid marriages between first cousins and seven states permit them only under specific conditions such as infertility, same sex, or advanced age marriages. Eight states make first cousin marriages a criminal offense. The latest states to forbid first cousin marriages are Texas and Connecticut in 2025.

Other states permit marriage between cousins if they undertake genetic counseling and understand the potential risks involved. 

Some states allow first cousin marriages with no restrictions. These include Hawaii, Alabama and South Carolina.

Six states forbid first-cousin-once-removed marriages. “Removed” in genealogy simply means how many generations exist between two people who share a common ancestor. For example, bride Mary’s grandfather was William and potential groom John is William’s great-grandson. This means they are first cousins but once removed. 

Two states, Kentucky and Nevada, forbid second-cousin marriages or first cousins twice removed. Online I found a notation that New York allows uncle-niece or aunt-nephew marriages in certain cases. 

Double first cousin marriages are usually forbidden in most states for good reasons. When two brothers marry two sisters and their children marry, they can be playing genetic roulette. Any hidden genetic disorder can surface even if the family doesn’t realize there is a risk. I know of several instances of sisters marrying brothers. The danger occurs if their children marry. 

While it may trigger your “ick” response, don’t be shocked to discover at least one cousin-cousin marriage in your own family tree as you research. 

Columnist Nancy Battick of Dover-Foxcroft has researched genealogy for over 30 years. She is past president of the Maine Genealogical Society, author of several genealogical articles and co-transcribed the Vital Records of Dover-Foxcroft. Nancy holds an MA in History from UM. Reader emails are welcome at nbattick@roadrunner.com.