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23andMe Ancestry Question

  • 02-03-2013 6:43pm
    #1
    Registered Users Posts: 562 ✭✭✭


    Hi guys I sent a sample off to 23andMe back in early February and I have a question I'm hoping someone here who knows about these tests might be able to answer.

    So I'm Irish and my family is Irish, however on my mothers side of the family we reckon that one of my great grandparents are originally from somewhere in the Mediterranean like Italy or Spain. (unfortunately my mother and aunts have no Idea of where they may be from and I have no living family members on that side to tell us)

    So my question really is will the 23andMe test results show it? Or are the gene pools in Europe to close for it to show up as something different? I dont know much about what the ancestry side of this test will show me so any insight from you guys would really be helpful.


Comments

  • Registered Users Posts: 714 ✭✭✭Ziphius


    I'm not sure if this is true in all situations but tracing ancestry is usually done using the Y chromosome (which is passed on from father to son) and/or the mitochondrial DNA (passed on from mother to child). These chunks of DNA are passed on through generations without being altered much so can be used to trace someone's ancestry and place it in a geographical location.

    The downside is that it will only look at a single strand of your ancestry. That is, if we look at the Y chromosome we will only be able to tell where your father's father's father's father's father (and so on) came from. Same with mitochondrial DNA though it would be you maternal line in this case.


  • Registered Users Posts: 562 ✭✭✭lcrcboy


    Ziphius wrote: »
    I'm not sure if this is true in all situations but tracing ancestry is usually done using the Y chromosome (which is passed on from father to son) and/or the mitochondrial DNA (passed on from mother to child). These chunks of DNA are passed on through generations without being altered much so can be used to trace someone's ancestry and place it in a geographical location.

    The downside is that it will only look at a single strand of your ancestry. That is, if we look at the Y chromosome we will only be able to tell where your father's father's father's father's father (and so on) came from. Same with mitochondrial DNA though it would be you maternal line in this case.

    right ok, I could be completely wrong here but from my understanding of 23andMe they show on the website your maternal and paternal line, so I dont think I will have an issue in that area. I was really just trying to understand whether if I had blood from Italy, Spain or one of those regions would it just appear as European and no different to Irish genes


  • Registered Users Posts: 108 ✭✭Gunnerkid


    In Ireland especially the West there is a high percentage of the population with R1b gene. So you will probably see this appear and we share this gene heavily with the people of the Basque region. So don't misjudge this to be your potential mediterranean relative. You may need to do further research into your family if the gene appears heavily in your results in order to clarify its origins.
    I think some north African genes could appear depending on what parts of these countries your relative could have come from (thinking Moorish and earlier mass movements of people)


  • Closed Accounts Posts: 5,995 ✭✭✭Ipso


    It depends on how long back you think the ancestor in question is. If it is within five generations you may get a larger than average for Irish in the Southern European component in Ancestry Composition.
    There is another feature called Ancestry Finder that lets you see who you share segments of your chromosome with, you may find thst you have small segments in common with people from a Mediterranean background.
    There is also a website called gedmatch.com that allows you to upload your raw data from23andme, there is a feature that allows you to run tools that may help you identify Southern European components.

    Irish R1b and Basque R1b are of two different kinds, the connection is that males in both populations shared the same male ancestor about 8,000 to 10,000 years ago. The Y haplogroup is only a tiny part of 1 out of 46 chromosomes.

    23andme look at your entire ancestry not just direct male and female lines (haplogroups) and they will identify your haplogroups.


  • Registered Users Posts: 714 ✭✭✭Ziphius


    lcrcboy wrote: »
    right ok, I could be completely wrong here but from my understanding of 23andMe they show on the website your maternal and paternal line, so I dont think I will have an issue in that area. I was really just trying to understand whether if I had blood from Italy, Spain or one of those regions would it just appear as European and no different to Irish genes

    So you are interested in if you can differentiate between Y (or mitochondrial) DNA from different countries?

    My understand is that yes, you can. However you can only do this with Y chromosomes or Motochondrial DNA.

    So if you Mediterranean ancestor was your grandmother's father this would not show up. That is, you would not inherit his Y chromosome. So it wouldn't be detected.


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  • Registered Users Posts: 714 ✭✭✭Ziphius


    Ipso wrote: »
    23andme look at your entire ancestry not just direct male and female lines (haplogroups) and they will identify your haplogroups.

    What else do they look at? My understanding was that Y chromosome and mitochondrial DNA were the only way to determine ancestry as they are passed on from one generation to the next (ie do not under go recombination).


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  • Closed Accounts Posts: 5,995 ✭✭✭Ipso


    Ziphius wrote: »
    What else do they look at? My understanding was that Y chromosome and mitochondrial DNA were the only way to determine ancestry as they are passed on from one generation to the next (ie do not under go recombination).

    The best way I can describe it is to draw your family tree for 10 generations, doesn't matter if you don't know the details just draw a template.
    At 1 generation you have two ancestors (parents), at 2 you have 4, at 3 you have 8 and for each subsequent generation the number doubles from the previous one (assuming no inbreeding). At 10 generations you have 1,024 ancestors in that generation timeline (for each generation you can use 2^n, n = generation number), add this to all the line above it and you have over 2,000 ancestors going back 10 generations.
    Now what Y DNA will look at is the direct male lineage, your father, his father, his fathers father, his fathers fathers father etc and in you tree of over 2,000 ancestors Y DNA will directly link 10 people. Y DNA is useful for trying to trace direct male lineages and from a big picture point of view it might give an idea of population movements.
    Now take the Mitochondrial DNA, this looks at direct female ancestry. It takes in your mother, her mother, her mothers mother etc all the way back through the direct female line. In the case of your 10 generation family tree you have now picked up 10 females.
    So using just Y DNA and mtDNA you have picked up 20 people out of over 2,000 but yet all these people have contributed to your genetic make up; your grand mother on your fathers side or your grand father on your mothers side etc
    The DNA that doensn't get passed down directly like Y & mtDNA is known as autosomnal and comes from the first 22 chromosomes. The technique used to determine shared ancestry with these other people is called Identity by Descent (I think), it looks at what shared genes you have with other people.
    Sorry if that is a mouthful but National Geographic used to have a great explanation on their website but it was taken down.


  • Moderators, Recreation & Hobbies Moderators Posts: 10,911 Mod ✭✭✭✭Ponster


    lcrcboy wrote: »
    So my question really is will the 23andMe test results show it? Or are the gene pools in Europe to close for it to show up as something different?

    The gene pools may well be different.

    Check out this blog post to see the type of results you can expect.


  • Registered Users Posts: 714 ✭✭✭Ziphius


    Ipso wrote: »
    The best way I can describe it is to draw your family tree for 10 generations, doesn't matter if you don't know the details just draw a template.
    At 1 generation you have two ancestors (parents), at 2 you have 4, at 3 you have 8 and for each subsequent generation the number doubles from the previous one (assuming no inbreeding). At 10 generations you have 1,024 ancestors in that generation timeline (for each generation you can use 2^n, n = generation number), add this to all the line above it and you have over 2,000 ancestors going back 10 generations.
    Now what Y DNA will look at is the direct male lineage, your father, his father, his fathers father, his fathers fathers father etc and in you tree of over 2,000 ancestors Y DNA will directly link 10 people. Y DNA is useful for trying to trace direct male lineages and from a big picture point of view it might give an idea of population movements.
    Now take the Mitochondrial DNA, this looks at direct female ancestry. It takes in your mother, her mother, her mothers mother etc all the way back through the direct female line. In the case of your 10 generation family tree you have now picked up 10 females.
    So using just Y DNA and mtDNA you have picked up 20 people out of over 2,000 but yet all these people have contributed to your genetic make up; your grand mother on your fathers side or your grand father on your mothers side etc
    The DNA that doensn't get passed down directly like Y & mtDNA is known as autosomnal and comes from the first 22 chromosomes. The technique used to determine shared ancestry with these other people is called Identity by Descent (I think), it looks at what shared genes you have with other people.
    Sorry if that is a mouthful but National Geographic used to have a great explanation on their website but it was taken down.

    Thank you for your reply.

    I am comfortable with Y chromosome and mitochondrial and understand their strengths and drawbacks with regard to tracing at ancestry.

    I was unsure if any other DNA was used to trace ancestry so will investigate how identity by descent works.


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  • Closed Accounts Posts: 5,995 ✭✭✭Ipso


    Also read up on autosomnal DNA, that's what IBD is used on.


  • Closed Accounts Posts: 5,108 ✭✭✭pedroeibar1


    Ponster/Ziphius, I’m more confused after reading all that! So what really will a DNA test tell me? Of my 8 gt grandparents all but my direct male ancestor have Irish surnames. For 14 of my sixteen gt gt grandparents it’s the same, but two in the female line (McDonnell & Lamont) from Northern Ireland possibly have earlier roots in Scotland.

    On the direct maternal line I have five generations with Irish surnames; on the male lineage I’m six generations ‘Irish’ (i.e. living in Ireland) but with an ‘English’ surname. I’m ‘highly confident’ that the earlier/next 2-3 generations were in Ireland and family lore connects me through them to an individual born England in the early 1600’s who died here in Ireland. That individual’s father is (generally accepted) the common ancestor of several branches of the family around the world. My ‘cousins’ in the UK can trace every male ancestor back to him – they from his first marriage, my line is (highly probable) from his second marriage.

    So, if I get a UK male ‘cousin’ to do Mito and Y DNA it will not tell us much on the mito side due to the different female spouses of the common ancestor? But the Y-DNA should conclusively prove a link? (The common ancestor is our Great x 9 or Great x 8 grandfather.) The autosomnal result will indicate from where the family ‘name’ originates?

    The options:-
    Familytree DNA has a 12 marker Y DNA test that costs $39
    Ancestry has a 33 for $149 or 46 marker for $179
    National Geographic costs $200 and tests 3,000 markers on mitochondrial DNA, and more than 10,000 markers on the Y chromosome.......
    23andme is $99
    Genebase has a $119 Y DNA 20 marker test and a 44 marker for $199.

    As I will (probably) have to pay for the tests anyone with suggestions or have experience of the foregoing? Which one would be most effective? Which one should I opt for?


  • Closed Accounts Posts: 5,995 ✭✭✭Ipso


    A Y DNA test done by you and your cousin would confirm if you share the same male common ancestor down the direct male line. Family Tree DNA are best for this but a 37 marker test is the better option.
    A mtDNA test is worthless to confirm the link with your cousin for the reasons you stated.
    An autosomnal test (23andme by far offer the best value) will give you a list of relatives who could share a common ancestor with anyone in your family tree. This kind of test is best used in conjunction with a good paper trail.


  • Registered Users Posts: 10 Paeru


    I think everyone's a bit confused in this thread. You don't need a separate test! :)

    X chromosomes and Y chromosomes DO recombine, albeit not as much as the other chromosomes. Mitochondrial DNA doesn't (for the sake of simplicity anyway).

    23andme has a feature where it will look at your autosomal DNA (everything that isn't your X and Y) and look for segments which are characteristic of specific regions. So to answer your question, it MIGHT show that a bit came from Southern Europe as opposed to the British Isles. It might not, even if some of the DNA is from Southern Europe, because it's "non-specific European DNA."

    So the answer is that it COULD show it, or your DNA could not be specific enough to show it.

    If you'd like, I could post my genealogy results from my 23andme to see what it looks like! :)


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