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DNA Analysis



  • Ancestry said they were holding back matches until the new ethnicity updates were released.

    I don't have a sibling tested there and admit I don't keep track of the number of 1st-4th cousin matches. I was updating some notes for a course I teach recently and noted I've had 100 new in that category since this time last year.

    Genealogy Forum Mod

  • Thanks for the reply. I got my ethnicity update last week but no new matches yet. We'll see.

  • I know what you mean VirginiaB. I have 327 of what Ancestry calls '4th cousins or closer' (though this also includes what they term '4th to 6th cousin'). My tally seems to be increasing by about one a month, but more recently all the new matches are a disappointing 21cM, with no tree, and no shared matches. My extended family are on MyHeritage too, where none of us have had any interesting new matches all year either.

  • Hi all,

    Apologies if this is not the correct thread, but just a question on DNA matches.

    My father got a message from someone on Ancestry who he has a 935CM DNA match with - I'm just wondering if this is a close or distant match (generally speaking) ? Seemingly this guy is surmising that his dad (passed away) and my dad were brothers. My dad has never known or met any relatives on his side of the family, hence joining Ancestry, so its totally possible, I'm just wondering if 935CM is a high or low number ?


  • 935cM is a very high match, but there's a few possibilities for the relationship. Some can be eliminated when you know the ages of both people.

    Take a look at this site

    Genealogy Forum Mod

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  • 935 is good high number but cousins might be more likely.

    The chart in this link will show you the likely relationships for a given range of cM's.

  • I was looking to bounce a Y-DNA question off ye, as I am still getting my head around it (being used to autosomal results).

    Over the years I have tested my DNA with the major companies (Ancestry, 23&me, ftDNA). The 23&me test give you your autosomal results but also tells you your Y and mT Haplogroups. Mine were gives as Y = I-CTS616 and mT = H.

    I wanted to go further down the Y-researching path so I took the Y37 test on ftDNA and they came back saying my Y = I-M223.

    My main question, and this may be just down to me not having my head around the different haplogroups, is why the difference?

  • so a STR test such as the Y37 will only guestimate what your haplogroup is based on the pattern of STR's. To get an accurate Haplogroup you need to do SNP testing. SNP's are single-point mutations where a DNA nucleotide mutates into another one. STR's are useful for finding close matches (within the last 200 years, though in some cases they'll show matches at deeper date) -- SNP's are more useful for understanding the structure of a lineage on deeper timelines.

    When such a SNP arises in a Y-Chromosome lineage it denotes a single point of common ancestry eg. all men carrying a SNP share descent in the first man to carry that SNP.

    In example above, M223 could be regarded as the 'ancestral' branch, whereas your I-CTS616 branch could be though of in terms of 'mutation B'

    Here some screenshot from FTDNA BigY tree showing structure of M253 and CTS616:

    simplified 'cookie trail' would be: I-M223 > I-P222 > I-CTS616

    eg. every CTS616+ man is also P222+ and M223+, however not all P222+ men are CTS616+ and likewise not all M223+ individuals are positive for P222.

    All three of these SNP's are very deep in time, I'm not fully up on Haplogroup I, but you are looking at branches of lineage that arose at least during the Bronze age. Going off the chart above the average CTS616+ individual has at least 145-150 SNP mutations occur in their Y-Chromosome since CTS616 mutated. It's for this reason that BigY testing is very powerful. As it allows you to discover every SNP mutation that has occurred and as more individuals do the testing you end up seeing connections show up. For example here is a tree showing McManus/O'Connor family of Connacht.

    R-BY18115 appears to have arisen during the period 800-1000AD, so far individuals who have tested positive it generally carry either surname McManus or O'Connor. We find individuals with surname McManus exclusively on left branches under R-BY18179, where as O'Connor's are found in all the sub-branches. The McManus family of Connacht is a cadet family of the O'Connor's having branched in the 12th-13th century. This BigY tree also includes a member of the O'Conor Don lineage which provides an anchor showing the link.

  • @dubhthach thanks so much for the very insightful answer!

    So I'll have to keep saving up for the Big700 unlock then :)

  • Well the tests are subsets, so for example if you have matches at 37 STR's who have tested further (say 67 or 111) you can always upgrade to that level to see if match holds true. Technically it would be cheaper then to update to BigY-700 from say 111 STR's. However in general I would always recommend people wait until sales (FTDNA do several a year) as you can make significant saving on any level of upgrade/new test.

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  • Yes I ordered my DNA test from Ancestry last march when they had a St Patricks Day special price and it took almost 2 months actually before I got the results back. Came back as expected almost all Irish with the focus on Leinster and Wexford specifically. Some Scottish and a little 2% Norway.

  • Mine were fairly similar 83% Irish 12% Scottish and 2% Norway. What are genetic community matches?

  • Genetic communities were a feature that Ancestry has done away with.

    Genealogy Forum Mod

  • I fall under IM223 also but I’m a few steps down. From reading about it M284 is below yours and then L126. Both of these, especially the latter, seem to have a connection to Scotland.