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Ancestry Matches 7cM and less

Discussion in 'DNA Questions and Answers' started by Andrew Lloyd, Jul 15, 2020.

  1. peter

    peter Administrator Staff Member

    I beg your pardon? DNA is absolutely perfect for solving mysteries like that!

    On average a quarter of all your matches will be connected through each grandparent so you have a wealth of information to go on. First eliminate the matches connected via your other three grandparents, then look for the common factors that connect the matches that remain.
     
  2. canadianbeth

    canadianbeth LostCousins Star

    I have tried that. They either have no trees or no shared matches. (there are a few with tiny trees; I have looked at the names in those and found that they come from the wrong part of England. And if they do have shared matches they usually match to each other. All of my known direct ancestors connect to the other three branches. Those to whom I have sent messages did not bother to reply. I even used Woodford for my search, since that is where my grandmother was working when she met my alleged grandfather, and got a very long list of names, some of whom matched to other branches of my tree. And of course, the first one was that 198cM person. So I then checked the 37 names in his tree and one of the surnames matching the possible dates was Pratt. When I put in Pratt and Woodford I got eight names, all with cM of 16 or less. The few with trees do not have the same ancestor's name as the one in CW's and none have any shared matches. I have put them all into a named group, "no shared matches".
     
  3. jorghes

    jorghes LostCousins Superstar

    I have a situation very similar to that in my mother's results - she has two distant cousins, one 197cM across 8 segments and the other 186cM across 7; both have small trees, and searching does not give me any shared surnames. I emailed one of them, and they gave me no more information than the general area where their family came from, which also didn't ring any bells. (They share DNA with each other, but none of the matches I have identified for my mother)

    I presume that they are related in some way to the father of my illegitimate great-grandfather, as I have known matches to each of my other great-grandparents on my mother's side, and these two matches shared no matches with them (I use colour coding to spot shared matches when assessing a match, even if I don't know where that person fits).

    But unfortunately, they're not the only "unknown family group" in my mother's tree!
     
  4. Helen7

    Helen7 LostCousins Superstar

    Looking through my son's matches of 6-8cM, I thought I could assume that if these matches didn't appear in either of his parents' match lists, they were probably invalid, and so was using this as a sort of 'filter'. However, I then came across a match of 8cM to a close relative of two of my matches whom I'd verified as genuine cousins (3C, 3C1R). The person who is not showing as a match to me but is to my son would be my 3C2R (and my son's 4C1R). So I can't really discard any of the apparently spurious matches in my son's list as they might be genuine:confused:. I think Peter mentioned such 'missed matches' across generations in another thread. I'm adding a note to those where there are 'common ancestor' flags or surnames of interest, just in case.

    Jorghes, do you have matches that don't appear in either of your parents' match lists? By the way, I'm impressed by the high cM numbers you are seeing in your mother's 'distant cousins'. Apart from my son, the only match I have above 100 cM is a second cousin, and my husband and I both have quite a few 2nd-3rd cousins but all below 150cM, some substantially so - for instance, my husband has a 2nd cousin who shares only 60cM. I wonder if we're unusual in having such relatively low cM numbers? I know DNA inheritance is random, but even so...
     
  5. Helen7

    Helen7 LostCousins Superstar

    My identified matches are rather unevenly split amongst my grandparents: 39%, 7%, 15%, 39%. I assume this is due to different family sizes and/or differences in how many people in each branch emigrated, especially to the US?
     
    • Agree Agree x 1
  6. peter

    peter Administrator Staff Member

    Those are NOT distant cousins!!!! They could be 2nd cousins of your mother or 2nd cousins once removed (so 3rd cousins to you). Or even half 1st cousins once removed.
    At the moment. But you can extend their trees, can't you? Your first objective is to find out how they are related to each other - presumably they don't know already otherwise you would have mentioned it.
    What proportion of her close matches have you managed to resolve?
     
  7. peter

    peter Administrator Staff Member

    The fact that you have verified someone as a cousin using historical records doesn't necessarily mean that a DNA match is valid (see Blaine Bettinger's post referenced in my recent newsletter); however, it certainly increases the chances quite considerably. The two main reasons why a match might appear to skip a generation are:

    1. Incorrect phasing - Ancestry use a phasing algorithm which is right most of the time, but it can never be perfect
    2. A misread SNP
    You can always investigate using GEDmatch (now back online).
     
  8. Helen7

    Helen7 LostCousins Superstar

    Yes, I realise that. And if I have DNA matches to a group of people closely related to each other (as in the case I mentioned), where their connection to me is also verified by historical records, surely that increases the chances that these DNA matches to me and my son are also valid. My son is a DNA match with all 3 of them, and I have been in contact with one of them who confirmed my other match is his uncle (useful to know as the uncle does not have a tree on Ancestry). The tree of my son's 8cM match shows her connection to them clearly too.

    Thanks for reminding me of the reasons for the apparent skipping of a generation.
     
  9. Pauline

    Pauline LostCousins Megastar

    Mine are unevenly split as well, with over twice as many matches on my mother's side, and most of those on my father's side being via his mother.

    However, I am still unable to identify which grandparent around half of my '4th cousin & closer' matches relate to, so the actual proportions may turn out to be vastly different from how they currently appear. Also, almost all of my '2nd & 3rd cousin' matches are on my mother's side, which has helped in identifying other matches on her side.
     
  10. peter

    peter Administrator Staff Member

    Not necessarily - a single spurious DNA segment could account for the matches.
     
  11. Helen7

    Helen7 LostCousins Superstar

    My match is 26cM across 3 segments with the uncle and 17cm across 2 segments with the nephew. Could that still be spurious? What is frustrating is that I have a shared match with both of them at 58cM across 3 segments with someone of my grandmother's surname, but who has no tree and doesn't answer my messages. These matches are amongst the 7% connecting to my paternal grandmother (less than a fifth the number linked to my paternal grandfather and maternal grandmother).
     
  12. peter

    peter Administrator Staff Member

    Matches of that amount are very unlikely to be spurious.

    Don't worry about the 58cM match who won't respond: focus on people who have trees, even if they don't appear so closely related. Distant cousins can be more useful than close cousins - the only reason we tend to prefer closer matches is because, other things being equal, it's easier to work out how we're related to them, but if they don't have a tree you may as well forget them. I have a match with a cousin who shares 3 times as much DNA, but has no tree, and doesn't respond - it's not something I'm going to lose sleep over.
     
    • Thanks! Thanks! x 1
  13. jorghes

    jorghes LostCousins Superstar

    Yes, there are matches attached to me that can occasionally appear to match one of my siblings, but neither of my parents, which to me always seems strange. I did have a contact from GEDmatch a long time ago who was in that very boat - a match to me, but not to either of my parents, so I'm not sure about the veracity of that particular match.

    My mother's results are actually on the smaller end of the scale, probably because my father's tree has a lot wider distribution in regards to emigration outside of the UK. And plus, he and my grandmother have larger proportions of Ashkenazi Jewish DNA, and there are a LOT of results linked to those parts of my tree.

    My mother's results tend to have less as there is less evidence of emigration into the USA - although I do know of some significant emigration into Canada and to Australia and the like.

    But equally my mother's matches are those where I know and have contact with a number of cousins who have also been DNA tested, so in some ways her results should be easier to sort. (even more so since they link to three out of her four grandparents)

    Whoops, my bad. They're actually sitting in the "3rd cousin" section of my mother's results at the moment.

    There are, unfortunately, no shared names at all - one tree only has 6 or so names, the other only 8. The only link at this point is both have someone who lived and or died in Rhode Island in the USA, but one has people in Lancashire and the other only from the US.

    So in regards to my mothers results - we have the following:
    Four results listed as "2nd Cousins" by Ancestry - and all are 2nd cousins (to my mother that is), two are related to my mother's paternal grandmother and the other two to her maternal grandmother and maternal grandfather respectively. (I know exactly where all four sit on the family tree). - these results share between 304 and 230 cM.

    Under "3rd cousin", there are 8 results. Two are the before mentioned unknown pair; 2 are a 2C and 2C1R (to my mother) on her paternal grandmother's line - both of these through either contact or Common Ancestors, I know where they fit; 2 come from her maternal grandmother's line (one I know exactly, the other I know through shared DNA) and the final two are linked through DNA to my mother's maternal grandfather's line, but I don't know their exact linkage, but they share significant DNA with results from the 2nd cousin section. (these results share between 197cM and 106cM)

    I haven't been as dedicated with the 4th cousin section, but I do colour code according to shared matches so I have an idea for many, and I make notes on specific relationships where there is a "Common Ancestor" tag (and that can also affect my colour coding).

    I don't have as many well known/contacted links with the branches in my other two main lines (my father and grandmother's results), but they also have numerically many more matches.
     
  14. jorghes

    jorghes LostCousins Superstar

    With thanks for the prompting Peter - I decided to attempt to construct a tree using the information given on the two as yet unknown links in my mother's DNA results, and I think with even the smallest search I may have found their linking surname - and discovered that they are first cousins.

    Unfortunately, it's not a surname I have on my tree.
     
    Last edited: Jul 29, 2020
  15. peter

    peter Administrator Staff Member

    That's great news - at last you have a real lead.
     
  16. jorghes

    jorghes LostCousins Superstar

    More than I had before. I did a search for that surname in the DNA results and a large number of results popped back up, so I might need to trace that name a bit further!
     
  17. peter

    peter Administrator Staff Member

    Debbie Kennett has heard - unofficially - that Ancestry are delaying the roll-out of the new matching until the end of August. If true this will give us a lot more time to save/investigate matches of interest which are below 8cM.
     
  18. Pauline

    Pauline LostCousins Megastar

    This is what Ancestry are now saying in their information on the update and distant matches.

    To quote:
    Based on customer feedback, we are delaying this change until late August so you have time to review and determine if you want to save any very distant matches by sending them a message and/or including them in a note or group.
     
  19. peter

    peter Administrator Staff Member

    Thanks - good to have this confirmation.
     
  20. Charles

    Charles LostCousins Member

    Sorry if this has been discussed elsewhere.

    I am not sure if I have found a flaw to the new rules that Ancestry is proposing.
    Here is my concern:
    I add a note to a John Smith (or add him to one of my groups) that I share 6cM
    This ensures that John Smith is kept on my list of DNA matches even though he has less than 6cM with me.
    However does the above action mean that I am saved on John Smith's DNA list?
    If not, it may mean that when contacted in 6 months time, John Smith is confused as I am not on his list.
    My question is do I have to message all the people with 6cM or 7cM that I am interested in (and get them to reply so they have sent me a message) to ensure that they are my list and I am on their list?

    This is important as I regularly use the little mentioned facility on Ancestry where I share my DNA matches with other users (as viewer) and ask them to do the same in reverse.
    This is very useful for distant cousins as they often share DNA with mutual cousins that do not share with myself.
    I have found literally dozens of 4th, 5th and 6th cousins that I have found by normal paper research that do not share DNA with me but have taken a DNA test and share DNA with other known DNA cousins.
     

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