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Shared Matches at Ancestry

Discussion in 'DNA Questions and Answers' started by Pauline, Jul 6, 2017.

  1. Pauline

    Pauline LostCousins Star

    I'm not sure I fully understand why this is the case, but does the converse apply - that is, if there is more than one shared segment the match is more likely to be within the expected range?

    I have what I refer to as a "gang" in my DNA matches at Ancestry, a group of almost 30 shared 4th cousin matches (around a fifth of all my 4th cousin matches), many of whom have trees, and I so far can't find my link with any of them, nor often their link to each other.

    Mostly we share between 20 and 35cM across 2 DNA segments, but with the few most distant of this group, the DNA is shared across only 1 segment.
     
  2. peter

    peter Administrator Staff Member

    The general rule is that most of our matches are likely to be at the more distant end of whatever range is quoted, simply because we have many more distant cousins (see the table in this article).

    Using the figures in that table, if Ancestry quote 5th to 8th cousins, it's about three times as likely that they're 7th or 8th cousins than 5th or 6th cousins, and nearly 20 times more likely that they'll be 6th, 7th, or 8th cousins than 5th cousins.

    Similarly, if Ancestry quote 4th to 6th (as they do for the matches that are headlined 4th cousin) you can see from the table that they've nearly three times more likely to be 6th cousins than 4th or 5th cousins, and over 20 times more likely to 5th or 6th cousins than 4th cousins.

    5th cousins share our 4G grandparents, of whom we have 64 (32 pairs). The chances that both you and your DNA cousin have both identified all 32 pairs (and done so correctly) is pretty remote - so you shouldn't be surprised that you can't find a match.

    Note: the shared matches you refer to are somewhat different - you should be looking at places not names.
     
  3. Pauline

    Pauline LostCousins Star

    Thanks Peter. I have been comparing places though without much success as yet. Most of my gang seem to have primarily American trees and as I don't have any American ancestry (as far as I know) I guess it may be that our link is with UK ancestors that they have yet to identify. I have been been trying to compare places in the US where I know relatives of mine emigrated to but no luck so far.

    I will keep plugging on, but I may take time out with an easier puzzle - trying to identify my 17th century Smith ancestors!
     
  4. peter

    peter Administrator Staff Member

    That's almost certainly the case, and it's another reason why those cousins could be more distantly-related than Ancestry indicates - the DNA pool would have been quite restricted in the 17th century.
     
  5. Susan

    Susan LostCousins Member

    I too have many matches with American trees. A lot of them have found all their ancestors back to births in the USA in the 1600s. But as most branches of my tree do not go back to the 1600s, it is impossible to say who the common ancestor was. These trees do not share any names with me. I do have a number of illegitimate ancestors. Although I know some of the fathers through the Quarter Sessions, I do not know all the fathers' names, and the link could be through one of them. Or they could be related via an as yet unknown female ancestor.

    I must confess to being surprised at how many of my matches can trace their ancestors to the 1600s in the USA. They must have been among the very early settlers.
     
  6. Bob Spiers

    Bob Spiers LostCousins Star

    If my regretful experience from being a member of My Heritage (MH) -thankfully a long time ago - and encountering many American (USA) members claiming to share part of my family, it was the work of a moment to realise such claims needed to be taken with a pinch of salt. Not only could I dispute their circa 1800 claims, those they took back even further -well before 1600 in fact - were often plainly laughable although they seemed to take them quite seriously.

    The USA have had a standing start on us as far as DNA matching is concerned and although one would think the science behind DNA might reign in those given to flights of fancy with normal research techniques, I fear it likely not so. Just a thought of course and I am sure not applicable to all, but be cautious.
     
    • Agree Agree x 1
  7. Susan

    Susan LostCousins Member

    It has occurred to me that it may be wishful thinking on the part of the owners of these trees. I have already come across this 'same name, must be mine' mentality in a branch of my tree. A 3 x great uncle and his family emigrated to the USA in the 1860s, and a number of his descendants' trees claim children for him who were born in different towns in England in the same year just because the quite common names of the parents were the same.

    The difficulty is finding out where their tree diverged from the truth, and who their ancestors really were.
     
  8. peter

    peter Administrator Staff Member

    I suspect that families in the US who can trace their origins to 17th century colonists have information that was passed down within the family, so it's likely to be reliable back to the point of arrival in the American colonies. However I get the impression that few have traced more than a fraction of their ancestral lines back this far - after all, I've only identified 22 of my 512 7G grandparents, and the records in England are generally easier to follow.

    The main problem is that because cousin marriages would have been relatively common in the colonies someone who shows up as an 8th cousin might really be a 12th cousin - and just about everyone with English ancestry is a 12th cousin of all the others (often many times over). So DNA is simply confirming what we already know.

    Stick to the strategies I outlined in the Masterclass and you're less likely to waste time on wild goose chases.
     
  9. Susan

    Susan LostCousins Member

    I did try following the process in your master class with the first few of these trees I found, but I could not find a connection by searching on surname, or birthplace. I have no unusual ethnicity (98% western Europe with a trace of Caucasus and north Africa).
    I looked for connections with the first 2 or 3 of these trees but now I don't. I still have nearly 400 pages to go through rather than waste my time on these 'wild goose chases'.
     
  10. peter

    peter Administrator Staff Member

    You can't pick a match and apply the strategies in the Masterclass to that match - that's the wrong way round. The strategies are designed to pick out the matches that are worth investigating.

    It's rather like LostCousins - I could randomly connect members and challenge them to find out how they are related (and they will be, believe me, if they go back far enough), but it's much more efficient to first identify commonalities.
     
  11. Susan

    Susan LostCousins Member

    I have to confess that my DNA matches have been put on hold for a while. I have only glanced at them over the last few weeks. Following an item in your newsletter I located and bought the will of my 4 x great grandfather from Lancashire Record Office via the transcriptions on Find My Past and this has opened up a whole branch of my tree which I am still researching. My DNA matches will have to wait! Once I have exhausted the information derived from the will and the second will I am awaiting, I will return to my DNA matches.

    I had started following the method in the master class but then the will arrived.....
     

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