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Overheard in GenForum: Double First Cousins
by Rhonda R. McClure

Each week Rhonda answers a question from the GenForum message boards and gives her expert answer here. We'd love to hear anything you have to add. Go ahead and leave your comments on GenForum with the original message.

December 28, 2000
See Rhonda's Previous Columns

Q: Patrick married Elizabeth. Patrick's sister Johanna married Elizabeth's brother, John. Their children were double first cousins. What does that do to the generations that follow? Does that change their level of kinship? It is certainly a stronger blood tie than if the cousins weren't descended from the same two families. -- Debbie

A: Kinship is often one of the most confusing aspects of our genealogical research. We are often trying to figure out how we are related to a fellow researchers. We are sure they are a cousin, but determining that relationship is sometimes difficult to pin down exactly, especially if you are new to researching your family tree.

Most of the time questions deal the word "removed" and what is a second cousin. However, there are a number of other relationships including double first cousins and others.

Kinship degrees can be confusing.

Double Cousins

A double cousinship occurs only when a set of siblings marries another set of siblings and both have children. This could be two sisters marrying two brothers. In your case, this is a brother and sister marrying a sister and brother.

Double cousins actually share the same gene pool as siblings. They share all four of the same grandparents. Most cousins share only one set of grandparents.

Cross and Parallel Cousins

First cousins can also be cross cousins. Cross cousins are those cousins who descend from a brother and sister. In your case, it was two sets of siblings, but they were still cross cousins.

There is another type of cousinship that is possible with first cousins. When the siblings are the same, as in two brothers or two sisters, the offspring, in addition to being first cousins, are also known as parallel cousins.

Affecting Further Generations

While double first cousins are double because they share both sets of grandparents, that is generally where such special references end. As you get to second cousins on down, the tree for proving this shows descent from a single individual. While these individuals would obviously be second cousins on many lines, that is where the special circumstance ends.

See Rhonda's Previous Columns

Rhonda R. McClure is a professional genealogist specializing in celebrity trees and computerized genealogy. She has been involved in online genealogy for fifteen years. She is the author of the award-winning The Complete Idiot's Guide to Online Genealogy, now in its second edition. She is the author of four how-to guides on Family Tree Maker. In late 2001, she wrote The Genealogist's Computer Companion. She is a contributing editor to Biography Magazine with her "Celebrity Roots" column and a contributing writer to The History Channel Magazine. Her latest book is Finding Your Famous and Infamous Ancestors. She may be contacted at

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