DNA Matching QUESTIONs

Rodger asked:

Sorry Kelly but I don’t follow you. Most of this DNA information reminds me of the matrix. Strings of numbers without any apparent meaning or order.

How do you know there is a match and what are you looking at/for?

Good questions. Lets review some basics of Y-DNA. There are two kinds of  Y-DNA MARKERS we look at. The Y-STRS and Y-SNPS.

Y-STRS= Y chromosome Single Tandem Repeats. These basically count the number of times a sequence of DNA is repeated as in ATGC repeated twelve times would give the marker a value or allele of 12. Each marker has a name as in the first FTDNA marker reported is DYS393. On the screen shot of our project below Group A has a value of 13 at DYS393. (Meaning the sequence was repeated 13 times) Groups A, C and D all share a value of 13 at this marker, however Group B has 14 (they got an extra repeat). There are approximately 400-500 Y-STRS that might eventually prove useful, however only 111 are currently available through FTDNA (The most in the industry). Y-STRS are what we use to match men to a common ancestor in a genealogical time frame. These changes don’t happen often but they do happen. In general we need to look at anywhere from 37 to 67 markers to see if two men are related. The more markers that match the higher the likelihood they are related. The more common a set of values is the more markers that are needed to make an accurate match. With the Wheaton Group B they have many unusual values at given markers so we can basically know someone is related if they match the first 5. This is highly unusual. In group D there are so many men with similar values they have a name for them which is the North Atlantic Modal Haplotype or NAMH for short.

Y-SNPS= Y chromosome Single Nucleotide Polymorphism. These report mutations or change in your DNA sequence at a specific location known as a locus. So in this case we have mutations that happened once in the history of mankind for each Y-SNP and all men bearing that mutation are distantly related. If we started with the proverbial “ADAM” the first mutation in Y-SNPs happened maybe 60,000 years ago and the tree became Haplogroups A and B. Each time a mutation happens it separates the tree into finer and finer branches. By following the tree we can trace any man from Adam to the most recent or “terminal SNP.” A terminal SNP is just the furthest down the tree branch we get a positive result. If we look at Group B below there Haplogroup is listed as R1b1a2a1a1b3c. However as new SNPs are discovered reading that jumble of letters gets harder and harder so it is easier to identify them by their terminal SNP “L2.” Group D is R1b1a2a1a1a4 or terminal SNP “L48.” You can see that the first part of the R1b….. is shared meaning that back 5,000 +/- years ago they shared a common ancestor. See the Chart on my Post on Wheaton Relationship A-D. Y-SNPs are what we use to match men to a common ancestor in ancient Haplogroups and where we chart where they came from. The hope is that as new SNPs are discovered like in a Walk Through the Y we will eventually bridge the gap between genealogical time and ancient time. There are about 60 Million Y base pairs where we might hope to find between 10-50 Thousand useful Y-SNPs. The new GENOGRAPHIC 2.0 will test 12,000 Y-SNPs of which only about 1 Thousand have been previously available. The old WALK THROUGH THE Y looked at about 400 thousands looking for NEW SNP mutations. The New WALK THROUGH THE Y will look at nearly 800,00 base pairs looking to find new SNPs. These SNPs if found can help define the Wheaton Group B and if shared by other L2’s further refine the Y Haplotree.

Okay now that I have your heads spinning lets look at a screenshot from our FTDNA page:

So looking at this screen shot we have a column across the top which is the Haplogroup which refers to the Y-SNPs we have just discussed. Those listed in Green have been tested those in Red are predicted. Those tested early on in a project will often have shorter predictions. Once a couple of matching folks have tested, FTDNA can make more refined predictions with higher confidence.

The next column is DYS393, then DYS390 and so forth. These are the Y-STR markers listed by name. The numbers in each row refer to the values or alleles that each man had at each Y-STR marker. I have clustered these into Group A, B, C and so on based on shared values or signatures. Even though the values look very similar at first glance the more markers you look at the more you can see differences. For each Group the MINimum, MAXimum and MODE or average is shown. So within a project I am looking for patterns and high levels of matching as in 24 out of 25 markers or 64 out of 67 markers. Some markers mutate faster than others. The fastest mutating markers are shown in Burgundy rather than deep Blue. All these things go into analyzing the match.
Now here’s what you can do (and I also do on your behalf). You can go to your own FTDNA HOMEPAGE and click on Y-DNA Matches. If you are in Group D and you set the threshold at 12 marker matches you are going to get pages and pages of matches because you have a very common set of markers known as the WAMH. However if you are Wheaton Group B you have very unusual values and you are ONLY going to have a few matches even at 67  markers and those are all a part of our project. You may want to sort at various thresholds and you may want to screen by name or part of name such as “Wh.”

Group C has a very interesting situation in that your closest matches also include a “group” of men surnamed DEAN. To THICKEN the PLOT these men with the surname DEAN are very close matches and they come from the same area in the borderlands between DEVON and SOMERSET in England. And in fact they lived in the same towns, specifically Chard and Chardstock during the 1500’s and 1600’s. We have the same situation with Wheaton Group B and WHEATONs and HANCOCKs. In neither case can I say which came first but I can tell you they have a common ancestor in Genealogical time (within the past 500-600 years). In each of these two cases the immigrant bearing the name came to America in the 1600’s so any NPE or name adoption needed to happen before the immigration. So which came first? There are several ways to approach this. One is to look for strong paper evidence for line of descent and the second is  to do broad sampling of DNA of men still living in the area bearing those surnames. Sheer numbers do not infer who comes first. Meticulous reconstruction of DNA trees and Paper trees may provide the answers. We get pretty attached to our names so people get understandably upset by the notion they may have been of a different surname at one time or another. First of all our DNA doesn’t give a hoot what we want. Second it doesn’t care what name we put on it. DNA is only going to tell you the TRUTH so if you don’t want to know then don’t do a DNA test ;-).

Another thing to do is click on your Haplotree and then click on the arrow this will give you an idea of where you are on the Y-Haplotree as defined by the Y-SNP markers I have discussed before.

IF SOMETHING HERE DOESN’T MAKE SENSE PLEASE POST A FOLLOW UP QUESTION.

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