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Kissin' Cousins


I'd like to update you with some more handy dandy charts, graphs and ideas on keeping track of who is related to whom in your family tree and how DNA is shared. We talked about cousins a few weeks ago in my "Are You My Cousin?" blog, and I will put a link at the bottom of this one that you can click there to review later if you like.

I have been charting and graphing how all these various DNA cousin matches from MyHeritage and Ancestry to find out the identity of the birth parents of my paternal Great Grandfather. The experts tell me that I need to find 2nd thru 4th cousins, because these are the people with whom I share Great Grandparents or Great Great Grandaunts or Uncles. Here is a great simple chart from FamilyTree Magazine. You can see that the whole "once/twice removed" indicates a separation by a generation, and that 1st, 2nd, or 3rd identifies which ancestor you have in common, grandparent, great grandparent, or great great grandparent.


I don't think we have talked about centimorgans yet. A centimorgan, abbreviated cM, is very very basically a unit of genealogical

measurement. When our cells divide and multiply the little DNA molecules inside them are also dividing, multiplying, and recombining with other halves. The proteins sitting next to each other on one half of the splitting DNA ladder tend to stick together when they bind up with their new half.

DNA helix

When you look at your DNA matches you will see how the computer thinks that you are related, how many shared cM's you have, and how much of the DNA is shared. The more DNA you share, the more closely you are related. Makes sense, right? We're are not molecular scientists trying to cure inherited problems like hemophilia or splice genes to cure cancer, so we don't need to go into the specific mechanics of recombinant DNA here.

The Shared cM Project headed by Blaine T. Bettinger at gathered DNA match data from thousands of people to establish a relationship chart showing the average amounts of shared cM's there were between relatives, as well as ranges of shared cM's because you will recall DNA does not replicate exactly between people. For example, your first cousin may share as few as 396 cM or as many as 1397 cM, but the average is 866 cM.

Shard cM Project

One of these has been printed out and thumbtacked to the wall right next to my computer screen. Sometimes I print one out for the different people I'm trying to line up, writing the applicable name of the cousin, parent, grandparent, great grandparent, etc. in the boxes to keep myself from getting lost in the trees, so to speak. A whiteboard can be very helpful for this too!

A spreadsheet can be used if that kind of tool makes you more comfortable and some word processing programs also have charting functions. The good people at FamilyLocket turned me on to that you can use to do all kinds of flowcharts on your desktop computer. This is a free site with no login or registration required, but does not seem to be a program for those who are not comfortable doing graphics work on the computer. You will need to have a cloud storage device or service, and they won't print by any easy method, but it can be useful when to sort who belongs to who.

magnifying glass

To find our missing person we have to find the most recent common ancestor that we share with our DNA matches. When we find a likely suspect you need to see who was in their family tree. Who where their parents? Who were their siblings? Did they have any children?

I am keeping track of these separate branches (aka "Quick and Dirty" trees) in my big Ancestry tree as separate trees. If and when I find the right connection, I can slide them in to my existing tree by editing their relationship. If you have a public tree and you insert some possibilities you have not proven, you want to be sure to mark anyone you are not SURE about with a "theoretical" or "actively researching" tag to prevent misinformation from being copied. This is the "Be Kind, Rewind" of genealogists (dating myself again, google it if you must).

As we discussed a couple of weeks ago, researching these different cousins to find the unknown ancestor will be harder if you are looking at matches with less than 40 cM's in common.

overwhelmed dog

Since I'm trying to find my great great grandparents I'm having to dive a little deeper into the 20's, and not finding much instant gratification! And to make things worse, I just found for the first time cousins that married cousins, which complicates the whole shared DNA picture. I don't want to think about that right now.

I'd rather think about something that would help you, my genealogy buddies! Got a question about your tree? Send me an email and let's talk.

Thanks for stopping by again this week,

Leslie Ryan

Not being compensated for any of these links or referrals. No copyright infringement is intended.


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