Friday, February 10, 2012

Claiming Kin

These two ladies are double third cousins and they met strictly by chance. Conversation led to discovery of common ancestors and the working out of their genetic relationship.

So what? In earlier times when transportation was lacking and communities were often isolated, young men sought wives five miles from home. Soon everyone in an area was related and it was important to know just what those relationships were from a genetic standpoint. We did wish to avoid the consequences of being "inbred hillbillies." While that's no longer an issue, the habit was well-formed and genealogy has become a hobby for many.

So just what do terms such as "double third cousins" or "second cousins once removed" actually mean? Here's a primer that will help explain:

When counting cousins, the number of generations between the people of concern and their nearest common ancestor is the degree of relationship. For example, the children of siblings are first cousins because there is only one generation (their parents) between them and the nearest common ancestors (their grandparents). Likewise, the children of first cousins are second cousins because there are now two generations between them and the nearest common ancestors (their great grandparents). The two ladies above are double third cousins because there are three generations between them and common great-great grandparents in two family lines. You see, their respective great grandfathers were brothers who took wives that were sisters, giving them two sets of shared great-great grandparents.

The expression once removed adjusts for differences in the number of generations between the two people of concern and their nearest common ancestors. For example, the relationship between one sibling's child and another sibling's grandchild would be first cousins once removed. The degree of relationship is always the smaller of the number of generations being considered. Thus, it would be possible to speak of first cousins thrice removed, although the utility of it might be questioned.

It's really all quite simple. Just write the genealogies down side-by-side and count the intervening generations. And as for our two ladies, although they share 4 great-great grandparents, there are another 12 great-great grandparents between them that are not shared.


  1. I've always wondered about that... now I can sit and work out all my family!

  2. It's not so bad if you write it all down, but for me whenever I'm trying to figure it out in my head it becomes so confusing.

    We still have inbreeding up in the hills here. Plus, their dialect (folks who live in the hills) is so very strong, I never can tell what the heck they're saying. I just nod my head and smile.

  3. Thanks for enlightening me on something which has been on my "must find that out one day" list for most of my life.

  4. I never used or completely understood the term 'once removed.' You were either a cousin or not. I used to really be into genealogy but have slacked off a little on my investigating. There are a few double first cousins in my husband's family, I think I have heard that that is the closest you can be without being a brother or sister to someone. Where I grew up just about everyone was related one way or another from being from the same 'distant ancestors.'