Um, how would you use Gedmatch if you weren't tested? The testing companies do just that - they test. Everyone complains that the companies are lacking when it comes it the interpretation. Go to any DNA lecture and you hear that. That's why some people have invented the 3rd Party tools. GedMatch is a 3rd party tool. It's not a testing company.
Just beware when you use 3rd Party tools. I've been to enough of those lectures. And privacy and ethics as well. On Fri, Sep 12, 2014 at 4:22 PM, A Faria <[email protected]> wrote: > Hi Doug, > > You have really put some hours into analyzing the data I personally am a > big fan of Gedmatch I think it is clear that Family Finder has some > shortcomings and you have effectively illustrated that Gedmatch is a very > useful tool as well. I think in some ways Gedmatch is superior to Family > Finder. > > Antonio > > > > > On Friday, September 12, 2014 2:13:15 PM UTC-7, Doug da Rocha Holmes wrote: >> >> Thanks to several private exchanges, I thought it might be interesting to >> illustrate one example of the use of Gedmatch. >> >> Fellow list member Antonio Faria, whose ancestry stems from Lajes do Pico >> on both sides of his family, long ago tested for Y-DNA and he has written >> about it countless times on this list how it leads straight to Baltazar >> Vieira born in the middle 1500s and from Sao Mateus, Pico. Decades before I >> met Antonio, I knew Baltazar Vieira was also my own direct ancestor and the >> fact Y-DNA testing revealed his J haplogroup which means he has direct male >> line Jewish ancestry was simply fascinating to me. But for years I wondered >> exactly how Antonio descended from Baltazar, because my ancestry is from my >> paternal grandmother whose parents were both born in Sao Roque do Pico and >> I had already traced all families there and still had no idea how Antonio >> connected to Baltazar. So last year we finally made contact and found that >> it was his grandfather or great-grandfather from Sao Roque who moved over >> to Lajes in the late 1800s. Then I was able to know who our most recent >> common ancestor on that line is. It turns out that on that line it takes 8 >> generations back to reach that ancestor and 9 generations for me to reach >> the same ancestor, making us 7th cousins, once removed. >> >> This means that his father and my father are 6th cousins, once removed >> from this particular ancestor. >> But there is another line which takes 6 generations for his father and 6 >> for my father to reach, making our fathers 5th cousins. >> >> These two proven lines (with many more remote connections I won't name) >> are not enough for FTDNA to show that our fathers are related. Sure, one >> could say that it's simply because one or both of them didn't get the DNA >> from that ancestor. So that's the basis of my liking Gedmatch so much to >> look at DNA matches from all angles. >> >> Just now I ran a comparison between my father's kit and his father's kit. >> I set the cM level down as low as it goes which is 1 and here are the >> results: >> >> There are 6 separate segments of common cM on 6 different chromosomes (5, >> 6 11, 14, 16, 17). Two matches are quite small in the 1 range, three are in >> the 2 range and the largest is a 9.5 cM segment on Chr 17. The total of all >> segments equals 20.5 cM. >> >> Genealogy research has proven we're related. Then DNA testing has >> confirmed it as above. Yet they don't show as a match on FTDNA. >> >> So now we compare Antonio's father to one of my cousins. My cousin's >> grandmother was my father's mother, so my father is an uncle here. And all >> this DNA is coming from my father's mother with all Pico ancestry. If she >> were still alive to test, she would surely match about double the number on >> her side of the family that my father matches, just like my father matches >> about double the number on his side that I match. >> >> First of all, Antonio's father shows as a match on FTDNA to my cousin, >> unlike my father. So the matching DNA my grandmother passed down to the >> parent of my cousin was greater than the matching DNA my father got from >> her. This illustrates why it's best to get all the older generations tested >> first (today if you can), but do not neglect to get all your cousins >> tested, as well as all your siblings. >> >> I ran the two kits (Antonio's father and my cousin) through the one to >> one DNA comparison with Gedmatch and found the following common DNA: >> >> Chromosomes 1, 3, 6, 10, and 14 all had at least 1cM of shared DNA >> segments of various sizes. The total came to equal 20.9 cM. Notice how the >> total for my father was 20.5. The smallest segment was in the 1 range, two >> segments are in the 2 range, one in the 3 range and the last and biggest >> segment is in the 11.4cM. That larger amount was enough for FTDNA to list >> it as a match whereas the 9.5 segment for my father was too low to reach >> the minimum threshold. >> >> I'm certainly no scientist, but I think that the two totals of 20.5 and >> 20.9 cM are significant. It's telling me that my grandmother had no less >> than 20.9 cM of this same matching DNA and could be way more, like 40 cM. >> But it's impossible to test that. >> >> The way I interpret it is that the matching DNA from my grandmother was >> pretty much equally passed down to my father and his sibling, then passed >> to my cousin. Too bad we can't test my father's sibling to know exactly how >> much matching DNA they had, but no matter what, my cousin got a tiny bit >> more of it and chances are pretty good there was more of that matching DNA >> in the parent. >> >> But the reason FTDNA called a match in one case and not the other is the >> size difference (11.4 verses 9.5). It is my understanding that this is only >> part of the equation when deciding who is a match and who is not. The total >> cM is the other part of the equation and since that is about equal in both >> kits, the only reason one is a match is the size is just a bit higher for >> one segment. >> >> But it's the randomness of DNA passing from generation to generation that >> accounts for the reason someone in a later generation shows as related when >> the closer generation (my father) doesn't show. By chance my cousin got a >> segment that recombined to form a larger segment that pushed them over the >> threshold and my father didn't, but got one additional segment showing up >> on some other chromosome. >> >> This is not the case, but let's assume we had just the two above common >> ancestors I mentioned where one line is a 5th cousin match and the other >> line is 6th cousins, once removed. Let's further assume that DNA for both >> sets of matches reached my grandmother. In fact, maybe DNA from one is >> completely missing, but for now let's say she got about 15cM from each >> ancestor and that the total cM she had equaled 30. She might have passed on >> about 10cM from each common ancestor so that my father got just a little >> over 20cM and my cousin got nearly the same. >> >> If there were two larger segments of about 10cM each representing these >> two common ancestors, I think my father would have shown up as a match. But >> by chance his 20cM was divided into smaller segments with only one larger >> segment that fell below the threshold. Yet my cousin, by chance, had a >> little bit larger segment that reached that threshold and ding, ding, ding, >> we have a match. >> >> In reality, there are many more ancestors we share that are quite remote >> from the 1600s and 1500s that probably account for some of these segments. >> Maybe the ones in the 1cM range are from these more remote ancestors. That >> throws a wrench into the above calculations, but that's just why it's more >> complicated than my above explanation. >> >> And that is also why FTDNA wants to error on the side of less matches >> than reality because it's hard to predict how segments all end up >> generation after generation. Same for any scientist and that's why they >> operate on hypotheses. They can't make any progress if they don't look at >> all the possibilities. And with their reputations on the line, they don't >> want to say something now that will be disproved next year, even if their >> hunch is right. >> >> But the data I have to work with, like above, is giving me a different >> conclusion than it's giving to FTDNA. They are not studying the same >> families I am. And it takes someone with a very complete family tree plus >> testing of many relatives to make these conclusions. I would be flattered >> if someone at FTDNA were to take my observations and add their vast >> additional expertise to come up with their own conclusions. It probably >> won't happen, but that's the reason feedback is so important. They will >> take a look at information and decide if it's worthy of their time. >> >> For now, the above is what I've observed. >> >> But before I end, there is one final comparison I can do that should help >> support my above conclusions. >> I can compare my own test to Antonio's father and this is what I get: >> >> Wow, this was not expected. We have a total of 22.2 cM in common. That's >> more than both my cousin and father. I don't show as a match to Antonio's >> father, either. None of my siblings do. And the reason is that I have mine >> broken down into more segments with the largest being 7.2cM on Chr 6. For >> my father, he had just 1.4cM on that chromosome. I had a second largest >> segment of 5.6 on chr 17 (notice that it's the same chromosome where my >> father's 9.5 segment lies). But I don't think it has much significance >> where the matching DNA shows on the various 22 chromosomes. That's just the >> random nature of it. >> >> Apparently my larger total cM than my father is coming from segments that >> are less than 1cM. No doubt my father had the same DNA which I got from >> him, but in my case, there was enough of it to randomly combine into more >> 1cM and larger segments that gave me a higher total. >> >> Another of my cousins has the following compared to Antonio's father: >> 15.3 cM total with the largest being 9.5cM which is exactly the size as >> my father's largest matching segment >> >> A sibling of this person above has a total of 17.1cM in common with >> another 9.5cM largest segment. >> >> Neither of these two above siblings show as matching Antonio's father. >> >> Yet another of my cousins, a sibling of the first who shows as matching >> Antonio's father at FTDNA has the largest matching segment of 11.8cM, just >> a little larger then the above sibling. The total amount of matching DNA is >> 20.2, but that's only the DNA that is 1cM or greater. I noticed that FTDNA >> says they have a total of 25.73 cM and that means about 5cM is smaller than >> 1cM in size. This helps explain why I had a larger total than my father. In >> fact, he must have at least the same amount of cM as I have, but some >> happened to recombine into smaller segments below the 1cM level. >> >> Finally, a third sibling of the two who show as matching Antonio's father >> does not show as a match through FTDNA. But when run through Gedmatch, >> there is a total shared cM of just 2.5cM on just one chromosome. This is >> clearly a case where they simply didn't get much of that DNA and instead >> got DNA matching other people. Yet another example why testing all siblings >> is important. >> >> I have been compiling this information for many hours, between other >> tasks. I think I have made my point. >> >> Hopefully I have convinced people of two things, at least: >> 1. get all oldest family members tested and also every possible cousin >> 2. study the results as I have done above if you already have tested many >> relatives and if you come to other conclusions than have I, please share >> them. This is how we all learn. >> >> Doug da Rocha Holmes >> Sacramento, California >> Pico & Terceira Genealogist >> 916-550-1618 >> www.dholmes.com >> >> >> > -- > For options, such as changing to List, Digest, Abridged, or No Mail > (vacation) mode, log into your Google account and visit this group at > http://groups.google.com/group/Azores. 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