Monday, March 14, 2016

Using DNA In Search of Roots - Sending DNA Tests To Potential Cousins

I had quite a complicated search and would like to share some of my search methods here as I think those methods may be able to help others in search. As my puzzle was difficult and the search was fairly long and complicated, I'm going to break it up into pieces so as to not overwhelm.

At one point in my search, feeling that I was getting nowhere, I decided to purchase extra DNA tests from Ancestry and try to find potential cousins who might be willing to take these tests. This was certainly a risk and required making some educated guesses. In this post I will discuss the method I used for deciding who I would send tests to.

A little background: I was adopted and obtained my original birth certificate which named my mother but not my father. I had found my mother, but she did not provide the name of my father. I have DNA results at 23andMe, Family Tree, Ancestry, and Gedmatch. While best advice says to have a parent tested when possible - I did not do this.

I have very few close DNA matches and none of those "New Ancestor Discoveries" on Ancestry. Comparing family trees of my closest matches did not provide common ancestors, and attempts at triangulation were fruitless despite hundreds of hours spent in such effort.

The closest match I was able to get in contact with was an estimated 3rd cousin on 23andMe. I had built a mirror tree for this cousin, but the mirror tree has a number of recent immigrants and brick walls and I was unable to identify which branch was mine using the trees of my more distant matches.

About a year into my search, I realized that I wasn't going to be able to get any further without finding more close DNA matches. I didn't know how long that would take - years maybe? if ever? Inpatient as I am, I decided to purchase several DNA tests at Ancestry, and set out to find potential cousins who might be willing to take those tests.

My closest cousins were anonymous matches on 23andMe and it took a while to get in touch with one of them who was a predicted 3rd cousin. Once I finally got in touch with this cousin, I learned that his father had also taken a dna test at 23andMe. His father was kind enough to share his results with me - and it turned out that his father and I did not share any dna with one another.

This indicates that the dna I share with this cousin, must have come from the cousin's mother.

If this cousin and I are indeed 3rd cousins (which was a reasonable assumption considering we're around the same age) then he and I would share a set of Great-Great-Grandparents.

The following diagram illustrates my Match's maternal family tree. He has four sets of Great-Great-Grandparents on his mother's side of his tree. One set are likely my Great-Great-Grandparents as well. We're assuming I am not related to his other three sets of Great-Great-Grandparents on his mother's side.

In this diagram, one of his branches are colored green, this is to indicate one line I could be related to him on. (please note that in these diagrams, I am selecting a line at random for the sake of demonstration. The actual line I'm related on may be different than the one shown.)

dia 1a



*please note, I started this with "assumptions" because I really had nothing more than assumptions to go on. As I gathered more evidence in my search, some of my assumptions were proven to be true, while others were disgarded. This was the technique I used.

This next diagram ads me and my line into this Match's tree (in blue). In this diagram, my match and I are 3rd cousins, sharing one set of Great-Great-Grandparents. The dna the match and I share, is dna we had both inherited from that set of Great-Great-Grandparents.

dia 2



In this next diagram, I am adding additional relatives (in yellow) who are also desended from that same set of Great-Great-Grandparents. These relatives would be people who would share DNA with my match and who I also expect to share DNA with me.

dia 3



In this next diagram, I am bringing in the rest of my match's family tree and other relatives of my match. (in gray & white)

Because I am not a descendant of my match's other Great-Great-Grandparents, I do not expect to share DNA with them or with any of their descendants.

The relatives in white would be expected to share DNA with my match, but not share DNA with me.

dia 5



Given what we know so far, I was unable to make any further determination without asking other family members to take a DNA test. The question would be - who should I ask to test?

The next relative who took the DNA test (he took the Ancestry DNA test and shared his results with me so that I could review his matches) was my Match's Uncle - circled in red in this diagraom:

dia 5a



When his results came back, I was hoping to find that he and I had matches in common that would confirm which branch of the tree I'm related on, however, this was not the case.

What he did have were two 2nd-cousin matches, shown in the following diagram:

dia 5b



His relationship to those cousins is shown in the following diagram:

dia 5c



Because I don't match those cousins, I ruled out the ancestors on that side of the tree as possible ancestors of mine, as illistrated in the following diagram:

dia 5d



Now I've narrowed it down to two possible sets of Great-Great-Grandparents and will need another DNA test to determine which of these couples are my ancestors.

We're going to switch gears here a bit now and look at my tree rather than on my match's tree.

The following diagram is my tree, with me in the center, in blue, and my ancestors in shades of blue. My match's line is in green on the left. (I used two shades of blue for my tree, the darker shade indicating the line I am related to my match on.)

The red line indicates the path of DNA inheritence - this is the path the DNA that my match and I share came down from our shared Great-Great-Grandparents.

dia 6



Also, in this diagram, the relatives in yellow are other relatives who would have also inherited DNA from these same ancestors:

dia 6b



Note how in the above diagram, all of the relatives in yellow and green would be related to one another and likely show up as DNA matches, as they are all descendants of the same set of ancestors.

Also note, that the relatives on the far right in the above diagram (in white) are related to me, but have no genetic relationship to my cousin on the far left (in green).

Let's go back and look at the following diagram again:

dia 5d



In the above diagram, I'm still left with two potential sets of Great-Great-Grandparents, and no clear way to determine which are my ancestors. Any of the relatives in yellow would be matches to both sets of ancestors, and so DNA results could be inconclusive.

To narrow this down further, I had to find a cousin who was related to one of these sets of Great-Great-Grandparents, but not the other.

The next DNA test was taken by a 2nd Cousin 1x Removed, as shown in the following diagram:

dia 7



The path of DNA inhertiance, from this set of ancestors to me, my match on 23andMe, and this new cousin, is shown in the following diagram:

dia 7b



In the following diagram, look at the set of Great-Great-Grandparents circled in Black. Notice that the cousin who had tested (far left) is not descended from this couple. The other cousins in the tree were descended from both of the couples in question - and so the last DNA had to go to a cousin who was descended from only one, but not both of these couples.

dia 7c



And finally, in the next diagram, where blue indicates my family tree, the relatives in yellow indicate the best relatives to ask to take a DNA test. On each, I have listed the relationship and the average length of shared DNA expected.

dia 8



Keep in mind that with each generation removed, the chances of not sharing DNA is increased, and the range of shared DNA widens. My numbers are from: http://isogg.org/wiki/Autosomal_DNA_statistics

You can find more information about the ranges of shared DNA here: http://isogg.org/wiki/File:Shared-cM-Project-Image-2.png

As for my search...

It took several DNA tests to go from finding a 3rd cousin to figuring out who my Great-Grandparents were. The results of the last of these DNA tests came in on my 47th birthday. It was really pretty cool, after so many years of believing that finding my roots would be impossible, to actually be able to confirm ancestors on my birthday!

I mentioned earlier that I relied on "assumptions" in this search. I had assumed that this match on 23andMe was a 3rd cousin and that the ancestors were Great-Great-Grandparents. I was still making this assumption when those results came in on my birthday. What I would learn later, as I was able to narrow my search down further, is that the ancestors were actually my Great-Grandparents, and the cousin on 23andMe is actually a 2nd Cousin once removed.

As I said, I had relied heavily on assumptions throughout this search. Many of them proved to be wrong, some proved to be close. When making assumptions, it's important to keep in mind that there can be many variables which could cause one thing to appear to be another thing - so keep an open mind and be prepared to switch gears when new information surfaces.

The day I decided to buy several extra DNA tests I had no idea who I would be sending those tests to. Ancestry was having a sale, so I was thinking that if I was going to do it, I better place my order before the sale ended. I was thinking in terms of, "build it and they will come". After placing the order, I gave a lot of thought to how I would go about asking potential cousins to test and who I would be willing to send those tests to.

I decided that it would be best to send the kits to one person at a time. Once the results of the first test came in, I analyzed, and then thought about where I should send the next test. This method proved to work and reduce the number of tests I sent to people I didn't match. And yes, I did have a test go to someone I do not match, but that will be the subject of a different post.

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