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Thread: Using Genetic Genealogy to Identify Research Projects

  1. #11
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    I definitely have some where I can see shared matches to multiple sides of my family. Part of it has to do with the size of the matches. It's also frustrating that Ancestry won't show shared matches that are too small -- I get they can be misleading, but would like to do that work myself.

    Often I find the shared matches, even one or two, can = a clue that I can use to find the connection.

    I tried to go through my matches beginning with the closest and assign them to each of my 4 grandparents. They've been broken down in more detail now, but putting them in those 4 buckets was helpful. (I definitely do not have the same number in each -- my dad's dad -- which has lines that go back to England and Wales quite recently -- has far fewer and for some reason those few who tested seem to have only tested at Ancestry, which is annoying. My colonial lines generate huge numbers of matches.)

  2. #12
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    Quote Originally Posted by msmarjoribanks View Post
    I definitely have some where I can see shared matches to multiple sides of my family. Part of it has to do with the size of the matches. It's also frustrating that Ancestry won't show shared matches that are too small -- I get they can be misleading, but would like to do that work myself.
    I have always figured it was my job to determine whether a match is "real" or not. But Ancestry is too reliant on Timber's elimination of matches that seem "too matchy". The reality is, not every person is affected by the same pile ups, and real ancestry can be reflected even in pile ups, anyway.

    I've used this example before, but I think it bears repeating. I am in a small DNA Circle in which everyone's "circle membership confidence" is listed as emerging. The focal person of the circle is actually relatively close, a 2nd great grandfather. Yet Ancestry only shows me as sharing DNA with two of the other three groups within the circle.

    Fortunately, the lead person in that group uploaded her data to GEDmatch, and I can see that we do share DNA. Not much, just 10.1 cM on chromosome 12. But it isn't as if Ancestry doesn't report matches of this size; they do, and I have many matches of this size in my DNA match list. That's why I believe Timber is the likely culprit in the match not being reported -- probably because Timber doesn't like something about the match location.

    Here's the thing, though. I am quite confident this is a valid match. The reason is, I have five siblings with data at GEDmatch. All five of them share DNA with my match -- and not just at the same location.

    • Sister #2 - chr 1, 23.5 cM; chr 8 - 33.0 cM
    • Brother #2 - chr 1, 24.5 cM; chr 8, 19.8 cM; chr 18, 17.9 cM
    • Sister #3 - chr 1, 24.5 cM; chr 12, 10.1 cM; chr 18, 17.9 cM
    • Brother #1 - chr 8, 19.0 cM; chr 18, 17.9 cM
    • Sister #1 - chr 7, 8.6 cM; chr 12, 10.1 cM


    You may notice that among the six of us, we actually share five different segments -- on chromosomes 1, 7, 8, 12, and 18. Some of these are over 15 cM in length, and a couple of them are over 20 cM. However, since none of my siblings tested at Ancestry, Ancestry has no way of knowing this. But I know, which is why I should be allowed to see the match and make the judgment.

    As it is, without GEDmatch I'd be left wondering why I don't match an apparent 3rd cousin. This does happen, but only about 10% of the time. And it actually didn't happen in this case. But my knowing it didn't is no thanks to Ancestry, since for whatever reason they chose not to report the match.
    Last edited by geebee; 08-28-2018 at 03:48 PM.
    Besides British-German-Catalan, ancestry includes smaller amounts of French, Irish, Swiss, Choctaw & possibly Catawba. Avatar picture is: my father, his father, & his father's father; baby is my eldest brother.

    GB

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  4. #13
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    Quote Originally Posted by msmarjoribanks View Post
    I definitely have some where I can see shared matches to multiple sides of my family. Part of it has to do with the size of the matches. It's also frustrating that Ancestry won't show shared matches that are too small -- I get they can be misleading, but would like to do that work myself.

    Often I find the shared matches, even one or two, can = a clue that I can use to find the connection.

    I tried to go through my matches beginning with the closest and assign them to each of my 4 grandparents. They've been broken down in more detail now, but putting them in those 4 buckets was helpful. (I definitely do not have the same number in each -- my dad's dad -- which has lines that go back to England and Wales quite recently -- has far fewer and for some reason those few who tested seem to have only tested at Ancestry, which is annoying. My colonial lines generate huge numbers of matches.)
    My close matches (> 20cM) have gone up, from less than a hundred a year ago to 267 now, so at least some of these are coming up as shared matches now. I found that some of my third cousins are matching at less than the 20cM threshold so it would be helpful if the threshold was a little lower.

    I have lots of matches to people whose Welsh ancestors emigrated in colonial times. I suppose that results from endogamy.
    All 32 3xgreat grandparents were Welsh. Two 6xgreat grandparents from England and a few Irish or English surnames before 1800. Paper trail shows several C11th to C14th Anglo-Norman lines and C11th Norse-Irish lines.

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  6. #14
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    I have a Welsh match I've been trying to identify my connection with. He's over 20 cM for me, but less for my sister, and could be back into the 1700s -- problem is, as I've mentioned elsewhere, that his tree doesn't go back beyond the larger towns that his various ancestors moved to in the second half of the 1800s, and my family came to the US from farming villages in the 1840s. I've traced some of those left behind, which is why I tend to think the match is farther back.

    For what it's worth, one of my Welsh ancestors in this line (surname Humphreys) came as a young man and I don't have many matches with his line other than those who are also descended from him (none outside of the US unless the mystery match is one). My other (his wife, surname Jones) came to the US with her parents and had several siblings, and I have lots of matches descended from those siblings (and even a DNA circle). It would be nice to know if the mystery match matches them, even if we are talking about small matches, as that would help me know which family and therefore which geographical area within Wales to focus on.

  7. #15
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    Quote Originally Posted by geebee View Post
    I have always figured it was my job to determine whether a match is "real" or not. But Ancestry is too reliant on Timber's elimination of matches that seem "too matchy". The reality is, not every person is affected by the same pile ups, and real ancestry can be reflected even in pile ups, anyway.
    I've grown to hate Timber. It doesn't seem to handle endogamy well, and as a result I have a lot of matches who also match my mom, but with less DNA than they match me (and they don't match my dad, and my parents have no shared ancestry). There is one person who matches me but doesn't match either of my parents on Ancestry, but over at Gedmatch this same person matches my mom. So obviously Timber wasn't recognizing this persons shared DNA with my mom but Gedmatch was (and the gedmatch kits were all uploaded from AncestryDNA, not from other companies - and we all tested on the V1 chip at Ancestry).

    Here's a list of my matches I've identified a MRCA with and you can see I've noted when I share more DNA with a match than my mom (there's a few for my dad too but not as many). Most, but not all, are from my endogamous Mennonite branch: https://docs.google.com/spreadsheets...c7sUOa/pubhtml

  8. #16
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    Quote Originally Posted by RobinBMc View Post
    I've grown to hate Timber. It doesn't seem to handle endogamy well, and as a result I have a lot of matches who also match my mom, but with less DNA than they match me (and they don't match my dad, and my parents have no shared ancestry). There is one person who matches me but doesn't match either of my parents on Ancestry, but over at Gedmatch this same person matches my mom. So obviously Timber wasn't recognizing this persons shared DNA with my mom but Gedmatch was (and the gedmatch kits were all uploaded from AncestryDNA, not from other companies - and we all tested on the V1 chip at Ancestry).

    Here's a list of my matches I've identified a MRCA with and you can see I've noted when I share more DNA with a match than my mom (there's a few for my dad too but not as many). Most, but not all, are from my endogamous Mennonite branch: https://docs.google.com/spreadsheets...c7sUOa/pubhtml
    Yeah, I've seen some folks who match my daughter without matching either her mother or me. But in at least a few cases I've been able to determine that the matches involve false negatives for me, rather than being false positives for my daughter. I'm sure that there are also some where the match is a false negative for my daughter -- not that the person is necessarily not related to her at all, but that he/she doesn't share that much DNA. Or at least, not from just one side.

    I'm not trying to argue that there should be no consideration of issues like pile ups. Just that pile ups are not the same for every person. There are some that are fairly common, but mostly they depend on the population groups you're part of. And some of them actually reflect fairly recent endogamy, rather than being more distant. In any case, you can't evaluate what you aren't allowed to see.

    So my plea to Ancestry is that it isn't necessary or desirable for them to make that decision. If an ordinary comparison between two people shows half matching, let me see it. Only exclude it if it's below 7 cM. Or they can use 10 cM if they want. Just let me see it, so I can decide how likely it is to be "real".

    In the case I mentioned, they were apparently suppressing a match with someone who was part of the same DNA Circle I belonged to. It would be possible that the match wasn't "real", but for 3rd cousins -- the relationship according to the circle info -- you'd actually expect some matching. Or at least you'd expect it for about 90% of your 3rd cousins.
    Last edited by geebee; 08-29-2018 at 12:53 AM.
    Besides British-German-Catalan, ancestry includes smaller amounts of French, Irish, Swiss, Choctaw & possibly Catawba. Avatar picture is: my father, his father, & his father's father; baby is my eldest brother.

    GB

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  10. #17
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    I think Ancestry's discounting is likely excessive, and I also hate that they won't have a chromosome browser. But if the complete opposite is MyHeritage, I find that a huge number of my matches are false -- they don't match either of my parents.

    I have a FF match at FTDNA I am interested in, because she's a mtdna GD1 match. But she matches my mom a little less than me on FTDNA, which makes me wonder if this is a IBD match (my parents aren't related, but outside of my mom's Swedish and my dad's Welsh are overlapping ethnically).

    My dad has a surprisingly high match from the 1700s on FTDNA, which may be due to intermarriage (non conformists in England). But one of the names is a name on his mom's side (colonial, Puritan, i.e., Calvinist from the same area, more than 100 years earlier) and there is an X match (albeit tiny). Match on multiple sides? Hard to say.

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  12. #18
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    Quote Originally Posted by msmarjoribanks View Post
    I think Ancestry's discounting is likely excessive, and I also hate that they won't have a chromosome browser. But if the complete opposite is MyHeritage, I find that a huge number of my matches are false -- they don't match either of my parents.
    So, having uploaded to MyHeritage I was ready to take the matches with a pinch of salt. It has been useful though. I found some matches that I recognised from Ancestry and GEDmatch and using the MyHeritage common matches facility I was able to untangle a few that just weren't making sense. I found that when my great great grandparents married in the 1860's, one from Pembrokeshire and one from Glamorgan, theirs wasn't the only marriage between their two families. One of my gg grandmother's male relatives had married one of my gg grandfather's female relatives. So I was able to reclassify some matches that looked like belonging to my gg grandfather and allocate them to his wife.

    Ancestry has a high cut-off point for common matches, and not many of my DNA cousins have uploaded to GEDmatch - it just happens that the cousins are on MyHeritage and the common matches threshold there is so much lower.
    All 32 3xgreat grandparents were Welsh. Two 6xgreat grandparents from England and a few Irish or English surnames before 1800. Paper trail shows several C11th to C14th Anglo-Norman lines and C11th Norse-Irish lines.

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  14. #19
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    I decided to do a comparison of cM matches with the rest of my family and between the different DNA companies. One reason why -- and why it fits here -- is that I had been worrying that there might be a NPE on my patrilineal line, which is the one I've been unable to confirm very far back (I've assumed because it's out of the US very quickly). My third cousins on that side seem a little too little related to me, but it was Ancestry, so I discounted it, and now my sister seems to be more closely related to those cousins, so I want to analyze that.

    Going to start with MyHeritage, however:

    The only "close family" matches for my family are each other -- my parents and my sister.

    My mom has 4 "extended family" matches, my dad has only 1 "extended family" match. I have 2 "extended family" matches (both shared with my mom), and my sister has only 1 "extended family" match -- the same as my dad's.

    For my mom's matches, I can identify all.

    Mr. K is a 187 cM match of my mother, and her 2nd cousin (estimated match is 46-515 cM [233 cM average, so pretty consistent]). He's a 92 cM match for me (expected would be 0-316, with an average of 123 cM, so not too far off), but only a 51 cM match for my sister, so if not for the rest of us she would have assumed a much more distant match. This was one of my "two extended family" matches.

    Ms. K is Mr. K's daughter, so my mom's 2nd cousin once removed. She is a 93 cM match of my mom (estimated match is 0-316 cM [123 cM average], so consistent enough. She's a tiny match of my sister and I, so within the range for 3rd cousins (0-217 cM), but without my mom we would have ignored her.

    Ms. G is a 92 cM match of my mother, and a 79 cM match of mine. She is only a 49 cM match of my sister. She is my predicted 3rd cousin by MH, but actually my 3rd cousin once removed and my mother's 2nd cousin twice removed. 2nd cousin 2x removed is predicted to be 74 cM (0-261), and 3rd cousin 1ce removed 48 cM (0-173 cM), so this is consistent again, with a slightly higher match than expected for my mom and me.

    Worth noting is that Ms. G is also a match of my sister and me on Ancestry. There she is said to share 73 cM with me (predicted 4th-6th cousin), and a 40 cM match with my sister (also 4th-6th). [Note: we match because we are descended from different daughters of my Swedish immigrant gg-parents, so it is possible that Ancestry's corrections affect this match less than some others -- I believe they tend to be more significant for American colonial ancestry.]

    My dad's one "extended family" match is Ms. D, and she is a 135 cM match, predicted 1st 2x removed to 2nd 2x removed, and she's also a 110 cM match of my sister, but only a 58 cM match of mine. She's around the same age as my sister and me, and the closest option for my dad's match is 123 cM [0-316], which is 2nd cousin once removed, which would mean my sister and I would be 3rd cousins -- 74 cM [0-217 cM]. If so, based on other common matches and surnames, good guess would be that we are all descended from my gg-grandparents on a particular side and that she would be descended from one of their 7 sons (I'm descended from a daughter). The area she lives in is consistent with that, but I have not managed to identify who she is yet.

    Going to compare some matches at FTDNA next, and then Gedmatch, as those are the only places I have all three immediate family members right now. Then will move on to my sister and my comparative matches at Ancestry.
    Last edited by msmarjoribanks; 12-04-2018 at 04:25 AM.

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