Known Relative Studies at FTDNA: Third Cousin Comparison and More Random atDNA Inheritance

I don't write about Family Finder very often for my known relative series since most of my close relatives have tested at 23andMe. Fortunately, my Travis third cousin recently decided to take the Family Finder test at Family Tree DNA. As a result, I have a new third cousin comparison to report.

Our only (known) common ancestors are our great great grandparents Abraham and Ruth (Stolebarger) Travis, so any matching DNA that we share is inherited from the Travises. Abraham's father Asa and Ruth's parents John and Sarah are two of my major genealogical brick walls, so it is really interesting to be able to isolate DNA that came from those lines.

My Travis third cousin and I share 45.96 total cM of DNA with a longest block of 14.84 cM. This is on the low end for third cousins and the most likely relationship suggested by FTDNA is actually fourth cousins. Only about 25 cM comes from segments longer than 5 cM, so just including those in my calculations (to keep it consistent with my 23andMe comparisons), that means we only share about .37% of our total DNA. Since third cousins are expected to share about .781% of DNA, this is a bit low, but it is in line with my other third cousin comparisons so far (averaging .39%). That's random atDNA inheritance for you!

Family Tree DNA offers a unique perspective on these comparisons, so I will share how this match looks on the different settings that are possible on their Chromosome Browser tool. In the chart below, the blue bars represent my twenty-two autosomal chromosome pairs. The orange bars are the sections where my Travis cousin and I have stretches of matching DNA. This chart is displaying the lowest setting in order to show all matching segments over 1 cM. Many of these are probably false positives, but it is still interesting to be able to see them.

My third cousin comparison showing all matching segments over 1 cM

The next image is set to show only matching segments over 3 cM. As you should be able to see, our main matches are on Chromosomes 2 and 14. The only other match that didn't drop off is the one on Chromosome 6. This match falls under the threshold of what you would see at 23andMe, so over there we wouldn't have known about it at all. Remember, this could be a "false positive" since a pretty large percentage of segments this size prove to be, but I will reserve judgment until I am able to compare it to my chromosome map (when it is more fully developed) to confirm if this segment falls in an area that I can positively attribute to my Travis ancestral line. That should help determine whether this is an authentic matching segment or not.

My third cousin comparison showing all matching segments over 3 cM

The final chart shows only the two largest matching segments. You can see them signified by the orange on Chromosomes 2 and 14. When you scroll over these spots, a window will open (as above) describing the exact starting and ending points of the matching segment(s).

Third cousin comparison showing only matching segments over 5 cM

To summarize, I compared a known third cousin to myself to identify the portions of our DNA that match each other. Due to the sizes, we can be confident that two of the matching segments are authentically inherited from our common ancestors. What this means is that I can now attribute those larger segments as originating with Abe and Ruth Travis.

Abe and Ruth Travis

If my Travis cousin were to upload his data to Gedmatch, I could compare him to my mother, sisters and some of my other cousins who have tested at 23andMe. It would be very interesting to see the variety of inheritance patterns. Hopefully, I will be able to do so in the future.

On another note, I actually have four matches on Family Finder who are predicted to be more closely related to me than my Travis third cousin. I have not found a common ancestor with any of these people mainly because, with the exception of one, they do not respond to my emails. It does make you wonder what would happen if everyone responded with great family trees, ready for comparison.

This should give some hope to those of you who are struggling to confirm common ancestors with your matches. We tend to focus on the larger matches, of course, but some of these seemingly lesser marches could still be quite significant.  As I have often emphasized, autosomal DNA inheritance starts getting pretty unpredictable at about the third cousin level. This comparison is a good example of that because we wouldn't usually expect a .37% match to have such a (relatively) recent connection. So, take a closer look at your match lists and give it another go. You just might be surprised by what you find!


*Another third cousin comparison: I found my third cousin today at 23andMe!*

Known Relative Studies with 23andMe: More Second Cousin Comparisons

Since my last post on second cousin comparisons at 23andMe was so popular, I have decided to expand on it. Another second cousin of mine recently tested at 23andMe. As a result, I have many more relevant comparisons to share with my readers. This cousin is also from my mother's family, but not on her Finnish side. Our common ancestral couple is Daniel Hewitt and Amelia (Travis) Proctor, my great grandparents. Daniel was born in 1866 in Equality, Illinois and Amelia "Millie" was born in 1870 in Sidney, Iowa.

Again, this is a great example of the random nature of autosomal DNA inheritance. My two sisters share 2.56% and 2.98% of their DNA with our Proctor second cousin, while I only share 1.07% of my DNA with this cousin. (The expected percentage of shared DNA with a second cousin would be an average of 3.125%.) Our unique patterns of inheritance can be clearly seen in the chart below. The long gray bars are representative of the 23 chromosomes and the shorter colored blocks signify the shared DNA between each person tested and our Proctor cousin. (For example, toward the end of Chromosome 1, Sister #1 and Sister #3 share the same small stretch of DNA with our Proctor cousin, but Sister #2 does not share any DNA with this cousin until Chromosome 5.)

Click on chart to enlarge

You can really see here that we inherited very diverse blocks of our Proctor great grandparents' DNA. One of  my sisters inherited almost two and a half times more of this "Proctor" DNA than I did, while my other sister inherited nearly three times more than I did. In fact, 23andMe predicts that we are only third cousins, but correctly predicts both of my sisters' relationships to this second cousin.

From this comparison, it would appear that my sisters ended up with significantly more DNA from our Proctor great grandparents than I did. However, since this chart really just illuminates the shared Proctor DNA with this particular cousin, it could be that my sisters happened to inherit much of the same DNA from Dan and Millie that our cousin did and I inherited almost entirely different blocks. To be sure, I would need to test more cousins descended from these ancestors to see if my comparatively low percentage of sharing continues.

This chart shows how my mother compares to her Proctor first cousin once removed (4.56%) and the DNA inheritance patterns of two of us daughters. You can see that the DNA was passed on quite differently to each with only three small areas of overlap between all three.

The chart below shows that my mother's sister inherited significantly more DNA in common with their Proctor first cousin once removed than my mother did: 4.56% vs. 8.55%.

Based on this, it isn't surprising that my aunt's two daughters in the chart below share much more DNA with this cousin than my sisters and I do (#1 = 4.49% and #2 = 4.69%) and with much larger areas of overlap between the three.

It is always interesting to me to see the inheritance pattern as the DNA is passed through the generations. The following charts demonstrate this with each comparing three successive generations to our Proctor cousin.

Lastly, the third generations in the charts above are second cousins once removed from this Proctor cousin. In the charts below, you can see, once again, that the amounts of common DNA inherited at this level of cousinship vary widely with very little overlap. (The only difference between the following two charts is the dark blue comparisons.)

The percentages of DNA in common for the second cousins once removed in this study were 2.91%, 1.22%, .76% and .33% (expected average = 1.563%). For second cousins, the percentages were 4.69%, 4.49%, 2.98%, 2.56% and 1.07% (expected average = 3.125%).

Dan and Millie Proctor (it's their DNA!)

A Lead from Y-DNA testing on my Travis line

You can read about the lead from Y-DNA testing on my brickwalled Travis line on my other blog here:

http://mytangledvine.blogspot.com/2010/08/my-elusive-great-great-great.html