April 19, 2019
For many people, extended family probably means grandparents, aunts, uncles and first cousins, but for genealogists, it can mean more distant relatives. In fact, it can sometimes be difficult to keep track of all of those more distant relatives and how they’re related to us. What, for example, is a fourth cousin twice removed? Without a score card, it’s hard to know. Sometimes even not so distant relatives can throw a monkey wrench into the family tree, especially in these days of widespread DNA test takers. While not as dramatic as heretofore unknown siblings or parents, double cousins and three quarter siblings can also cause surprising results.
Double cousins are relatively common, especially in certain families where marital partners are circumscribed because of location or beliefs. Double cousins result when two siblings marry two siblings from another family. My paternal grandfather was one of eleven siblings, but he also had eight double cousins because his father and his uncle had married a set of sisters who became his mother and his aunt. He and his cousins were close throughout their lives and regarded each other more as siblings than as cousins. When my grandfather married and had his own children, those children called his double cousins Aunt and Uncle rather than Cousin. Had my grandfather and his double cousins been able to take DNA tests way back when, they would most likely have shared about 25% of their inherited DNA, about the same amount as half siblings would share. Non-double first cousins share only about 12.5% of their DNA since they only share DNA from one parent’s family. So, when I eventually took a DNA test, the descendants of my grandfather’s double cousins turned out to be more closely related to me than the descendants of his other, non-double cousins.
A somewhat less common type of relationship is a three quarter sibling. A full sibling shares both parents and a half sibling shares one parent, but a three quarter sibling shares one parent and the other parent is a sibling of his/her other parent. Since some of my ancestors were early Latter-Day Saints, there is polygamy in my background. My second great grandfather was married to three different women at the same time, and two of the women were sisters. The children of those sisters were three quarter siblings; if they’d taken DNA tests, they’d have shared about 37.5% of their DNA, and the descendants of the sister who was not my second great grandmother are closer matches to me than the descendants of the third wife, who was not related. In addition to polygamy as a cause for three quarter siblings, a widow or a widower, in earlier times, often married the sibling of his/her deceased spouse. It was believed that an uncle or an aunt would be more interested in raising the orphaned children of his/her sibling than a non-related person would be. If the second marriage produced offspring, they would be three quarter siblings to the first group of children. Three quarter siblings are not very common now, but they do occur.
Finally, there are cases of relatedness that almost defy logic when it comes to describing them. One such case concerns a collateral relative of mine. A young woman (we’ll call her Young Wife) married a much older man, and they had several children. Old Husband (as we’ll call him) had been married before and had several children with his first wife. After Old Husband and Young Wife had been married for a number of years, Young Wife decided that she didn’t really want to be married to Old Husband and that she really wanted to be married to his oldest son (Oldest Son) by his first wife. After a quick divorce from Old Husband, Young Wife married Oldest Son, and they had four or five more children. At this point, Young Wife had two sets of children by two different men, who were father and son. The relationships between this group of people are interesting, to say the least. Oldest Son was the father of one set of children with Young Wife, but he was also the half sibling of Young Wife’s children with Old Husband. As for Old Husband, he was the father of some of Young Wife’s children, but he was the grandfather of the others. The relationships among this family quickly get difficult to keep straight, but it’s easy to imagine conversation-stopping introductions such as “Hi, I’m Young Son, and this is my daughter and her sister, who is also my sister.” Although situations like this family’s aren’t too common, they do exist, and the wise researcher probably should keep the possibility in the back of his/her mind when trying to figure out families.
Knowing how two people are related is important to traditional genealogical research and even more important to genetic genealogy, but sometimes the relationships turn out to be anything but straightforward. Or, at least it seems that way in my family.
Researcher/Director at Large