For the next four months, I will focus on presenting the stories of our Genetic Tree ancestors. Today’s blog will go over the basics and get everyone familiar with the different terms I will discuss, such as “What is a genetic tree?”
Genealogist have been tracing their Family Trees for hundreds of years, using records and family stories to assemble their family trees. For the last ten years, DNA has been changing the landscape of family history research. Understanding the basics of DNA and how we inherit those genetic building blocks will help with understanding how limited our Genetic Tree is compared to our Genealogy Tree.
There are three types of DNA: y DNA, Mitochondrial DNA, and Autosomal DNA.
yDNA
y DNA is the male Y chromosome that is received from the father, who received it from his father, who received it from his father, who received it from his father and continues back ( see the chart below and follow the light blue boxes). Changes to the Y DNA occur slowly (a random number of generations), making it unsuitable for finding specific cousin relationships. But will show if two or more male individuals are from the same paternal ancestral line.
Mitochondrail DNA
Mitochondrial DNA (mtDNA) is similar in that it follows the maternal line of inheritance over time. Unlike the yDNA, mtDNA is inherited by all of the mother’s children, but only the females pass it on. Like the y DNA, the mtDNA is slow to mutate and is not useful in discovering your more recent cousin relationships. The chart below shows the maternal or mtDNA line of inheritance in light pink.
Autosomal DNA
Autosomal DNA (atDNA) are the 22 Chromosome pairs we each receive from our parents. We receive approximately 50 % from our father and 50% from our mother. That 50% is made up of approximately 25% from each of their parents, whose 25%, about 12.5%, came from each of their parents; each generation you get approximately 1/2 of what you received from the previous generation. So, by the time we reach our 5xgreat grandparents, we may have less than 1% of their DNA. Therefore, autosomal DNA is great for determining cousin matches from some of our more recent common ancestors.
Testing And what you get
Decide what you want to learn from your DNA, and choose a company accordingly. My first test was with 23 & Me in March 2013 (atDNA + the x Chromosome). At about that same time, we had my brother and a first cousin on our maternal line do a y DNA test with Family Tree DNA. In 2018 I uploaded my 23 & Me test data to My Heritage.
With autosomal DNA testing, we must understand that it is not magic. No marker says what you inherited from your mother is here. Most companies will tell you how many centimorgans (cMs) you share with each match. The higher the number the closer the match. Here is a link to the “Shared cM Project 4.0 tool v4,” by Blaine T. Bettinger at DNA Painter: https://dnapainter.com/tools/sharedcmv4 . Putting in the number of shared cMs you share with a match will quickly show what the relationship may be.
In the example above, I put in the total cMs I share with a known third cousin on my maternal side; I will call him H1. The “Shared cM tool” tells me that there is a 31% probability that H1 is either a half 3rd cousin, 3rd cousin once removed, a half 2nd cousin twice removed, or a second cousin 3 times removed. With only a 22% probability that he is a 3rd cousin. H1 is related to me through my 2x great-grandfather, John Woolley Heap, and his wife, Richmal Hall. Without having done an extensive tree, it may have taken longer to figure out from which ancestral couple we both inherited the same 60cM.
My Genealogical Tree vs Genetic Tree
My Genealogical Tree includes me (1), (2) parents, (4) grandparents, (8) great grandparents, (16) 2x great grandparents, (32) 3x great grandparents, (64) 4x great grandparents, (128) 5x great grandparents. That equals 255 individuals. Then, I start adding all of my ancestor’s siblings. My GenelogicalTree includes a total of more then 2,000 individuals. If your 3x great-grandparent couple had 12 children that survived to adults, you could have a minimum of 192 third cousins. How many first cousins do you have? If your tree is composed of large families in the first few generations, your cousin matches with your DNA and will probably be populated with quite a few cousins you may already know. If your first three generations are small families you will have fewer matches in the first and second cousin range.
Samuel Hall & Sarah Coe
Let’s start with Samuel Hall and Sarah Coe.
The above shows three matches to me from Samuel Hall (1798-1869) and Sarah Coe (1799). According to each matches tree, which I found at several different places, they are all related to Samuel Hall and Sarah or Sally Coe. Sally is a nick name for Sarah (see Family Search for more https://www.familysearch.org/en/wiki/England_Female_Nicknames_-_International_Institute).
Match #2
Match #2 is a known third Cousin. This match’s great grandfather is my great grandfather’s known brother. So, their parents, John Woolley Heap and Richmal Hall are our most recent Ancestors in common. We share 54.8 cM of their DNA. Using the tools at DNA Painter we can see if this number falls into the expected amount for third cousins.
According to the Shared cM Project 4.0 tool v4, at DNA Painter, the average is 73cM, and the numbers for third cousins range from 0-234cM. While our shared cM is below the average, it is within the acceptable range.
Match #3
Moving over to Match #3 the shared cM is 53.2. Looking again at the tool on DNA Painter, we see that the average cM for fourth cousins is only 35 cM while the range is 0-139 cM. So my first question was, why is this high? I noticed that Fanny Hall was married to a Gee. I know that Ada Heap’s, maternal grandfather’s sister’s second husband was James Gee and that the Gee family originated in the same area of Lancashire and Cheshire, England, where the Heaps immigrated from. I have not found a second connection for Match #3, but I know there is a possibility.
Match #4
Match #4 is a supposed match through a sister to my Richmal Hall, making this match also a descendant of Samuel and Sarah (Coe) Hall. I share only 17.4 cM with this match. As with Match #3, the average fourth cousin shared cM would be 35 with a range of 0-139. Using the DNA Painter tool once again, we find that this match is more likely to be one of the following: 6C, 6C1R, 5C,6C2R, 4C1R, 5C1R, 7C, Half 3C2R, 4C2R, 5C2R, 7C1R, 3C3R,4C3R, 5C3R, 8C, or more distant. I have not identified this as a sister to Richmal Heap. This is where research of the records will help to identify how Match #4 is actually related.
This is a complicated subject and process. I hope I was able to provide a nit that may be helpful. As always please make any comments below and of clik the like button if you enjoyed this post.
