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Thread: Puzzling Ancestry Composition result in relation to X chromosome

  1. #1
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    Puzzling Ancestry Composition result in relation to X chromosome

    I wasn't sure whether this fit better under 23andMe results or here, since it pertains to both.

    I'll start by saying that I generally like Ancestry Composition and consider it, while still not perfect, a great improvement over Ancestry Painting. I particularly like the ability to use different estimates and views -- such as split view, for me, since my father has tested.

    Overall, I would say that the speculative estimate actually comes closest to my paper trail estimate of ancestral origins -- except for the X chromosome. This one is a bit of a puzzle, because the speculative estimate shows my X chromosome as very nearly 100% "British and Irish".

    And, I do in fact have both British and Irish ancestry. But the vast majority of this ancestry is on my father's side, and since I'm male my X ancestry is only on my mother's side.

    I did an estimate of my potential X contributors going all the way back to my 8th great grandparents. There are some unknown names, but I think that in most cases I was able to identify likely immigrant origins. Of course, there's an assumption that if the immigrant was from, say, France they should be counted as "French".

    Anyway, I came up with 26 8th great grandparent (potential) X contributors who were likely German. There were another 21 who would likely have been Alsatian -- and these seem mostly to have had German names. There were also 15 of probable French origin. 13 were from the Spanish (Catalan) island of Menorca. 2 were Swiss. Another 2 were likely Choctaw, but I counted them as 4 since they appear in my genealogy twice.

    Only 9 of 77 of the 8th great grandparents who might have contributed to the X chromosome (if I didn't make some math error) seem to have been of British or Irish origin. That's less than 12%, but supposedly my entire X chromosome is British?

    Of course, it's entirely possible that there is one or more British of Irish NPE among these ancestors. Or the count might be off for some other reason. (For example, once I got back to Menorca, I assumed all ancestors were Catalan. But the island was under British control for at least part of the 18th century, before my ancestors immigrated from there. The ones I know about had Catalan names, but ....)
    Last edited by geebee; 04-10-2013 at 05:57 AM.
    Besides British-German-Catalan, ancestry includes smaller amounts of French, Irish, Swiss, Choctaw & another NA tribe, possibly Catawba. Avatar picture is: my father, his father, & his father's father; baby is my eldest brother.

    GB

  2. #2
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    I think this might have to do with how the X is more conserved than autosomes: (1) males do not recombine it; (2) because males only have one copy, fewer mutations are possible so n cM might mean less for the X than for an autosome; and (3) females may but do not always recombine it. All this leaves us with autosomal-like recombination but on a much longer time scheme than what we would see for autosomes.

    Why would this bias things toward the Isles? Maybe because the customer database is mainly American, 23andme is guessing that "unspecified American" means Isles; perhaps this effect is similar to the apparently overreported Scandinavian and Isles in dna.ancestry.
     

    Other ancestral Y lines:

    E1b-M81 Ukraine (Ashkenazi)
    E1b-V13 England
    I1-M253 Ireland
    I2-M423 Ukraine
    R1a-L176.1 Scotland
    R1b-L584 Syria/Turkey (Sephardi)
    R1b-L20 Ireland
    R1b-L21 (1)England; (2)Wales?>Connecticut
    R1b-L48 England
    R1b-P312 Scotland
    R1b-FGC32576 Ireland

    Other ancestral mtDNA lines:

    H1b2a Ukraine (Ashkenazi)
    H6a1a3 Ukraine
    K1a9 Belarus (Ashkenazi)
    K1c2 Ireland
    V7a Ukraine

  3. #3
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    Well, here's an addition to the puzzle.

    Since our father's data is available and he is on our tree, presumably the data in phased before being used in Ancestry Composition. (I think it may be anyway, but with less certainty.)

    If my single X chromosome is truly "British and Irish", then to the extent that my sister or brother matches my X chromosome, theirs should also be reported as "British and Irish", right?

    Well, my sister and I do have some "half identical matching" on the X. Or to put it another way, part of her maternal chromosome is identical to my own. Yet none of her maternal X chromosome is identified as "British and Irish". (None of either of her X chromosomes, in fact.) All of her maternal X is identified simply as "nonspecific northern European", including in regions which the two of us share. And that is not a trivial amount, but consists of virtually the entire chromosome to the right of the centromere (in the depiction), and a small segment to the left.

    Likewise, one would think that since any matching between my brother and me on the X chromosome must be fully identical matching, any region which is "British and Irish" for me should also be "British and Irish" for him. Yet this he not the case. A portion of his X chromosome -- less than half -- is identified as "British and Irish", and it does include a small amount of the chromosome that we have in common. But other regions we have in common are not identified as "British and Irish" in him, even though they are in me.

    EDIT: I should probably also add that if my X chromosome is in fact of "British and Irish" origin, then at least one of my daughter's should be too. In fact, both of hers are. So this is at least consistent.
    Last edited by geebee; 04-10-2013 at 04:44 PM.
    Besides British-German-Catalan, ancestry includes smaller amounts of French, Irish, Swiss, Choctaw & another NA tribe, possibly Catawba. Avatar picture is: my father, his father, & his father's father; baby is my eldest brother.

    GB

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    Hm. There's also problems with 23andme's phasing engine for AC right now. If you're interested I'll post an example.
     

    Other ancestral Y lines:

    E1b-M81 Ukraine (Ashkenazi)
    E1b-V13 England
    I1-M253 Ireland
    I2-M423 Ukraine
    R1a-L176.1 Scotland
    R1b-L584 Syria/Turkey (Sephardi)
    R1b-L20 Ireland
    R1b-L21 (1)England; (2)Wales?>Connecticut
    R1b-L48 England
    R1b-P312 Scotland
    R1b-FGC32576 Ireland

    Other ancestral mtDNA lines:

    H1b2a Ukraine (Ashkenazi)
    H6a1a3 Ukraine
    K1a9 Belarus (Ashkenazi)
    K1c2 Ireland
    V7a Ukraine

  5. #5
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    It's definitely been interesting to see how different various tests can be.

    FTDNA has me down as "100% European, ±0.01%". The specific populations are Finnish, Russian, Spanish, Tuscan. Of these, the only one actually in my paper trail is Spanish, and that should be no more than about 12.5%.

    Ancestry says "48% Central European, 23% Scandinavian, 16% Eastern European, 6% Finnish/Volga-Ural, and 7% uncertain". (Of course, if you look at their map, "Eastern Europe" includes both Lithuanians and Greeks -- which seems like a pretty ill-defined category.)

    Doug McDonald says "69.5% Irish, 6.9% Spanish, 22.7% Jewish, and 1% Na-Dene". (He said he believe the Native American portion was actually closer to 2%.)

    And Ancestry Composition says "97.3% European, 2.0% East Asian and Native American, <0.1% Sub-Saharan African, and 0.6% unassigned". Virtually all of the "East Asian and Native American" is further identified as simply "Native American", and the "European" is broken down as "36.1% British and Irish, 9.1% French and German, 0.5% Finnish, 38.8% nonspecific northern European, 2.2% Italian, 1.3% Balkan, 1.0% Iberian, 4.1% nonspecific southern European, 0.7% Eastern European, and 3.4% nonspecific European".

    By my paper trail, I should be (roughly): 1/2 German; 1/4 British (mostly Scottish and Scots-Irish); 1/8 Spanish; and 1/8 left over for Dutch, Belgian, Swiss, French, and Native American (thought to be Choctaw).
    Besides British-German-Catalan, ancestry includes smaller amounts of French, Irish, Swiss, Choctaw & another NA tribe, possibly Catawba. Avatar picture is: my father, his father, & his father's father; baby is my eldest brother.

    GB

  6. #6
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    23andMe bases these Ancestry Composition origins to least 500 YPB, correct? My Mother is all Italian. Her Maternal Grandparents were from Tuscany, her Paternal Grandmother was from Campania, and her Paternal Grandfather was from Abruzzo. All family surnames were of native Italian and history. On Standard, my X Chromosome is about 90% Italian, nearly 10% Nonspecific Southern European, and a tiny fraction Nonspecific European. In Conservative, it's about 80% Italian, nearly 20% Nonspecific Southern European, and that tiny bit Nonspecific European. In Speculative, it's about 95% Italian. Nearly 5% is now Nonspecific Southern European, and this does not shift into the other References of either Iberian or Balkan, BUT the fraction of Nonspecific European becomes Nonspecific Northern European. Seeing as how the Speculative mode is below a 50% threshold, I really don't believe it's picking up on any genuine North European. Part of the Tuscan side was from the Apuan Alps, and I'm sure getting that far up, it can't be surprising if there is some ancient genetic affinity to say people in Switzerland or France, without there necessarily having to have been North European Admixture. Afterall, the area was once part of Pre-Roman Liguria (Ligures). The fact that the Nonspecific Southern European even below a 50% threshold isn't even hypothetically Iberic nor Balkanic, to me means I don't have genetic similarities to say Spaniards nor Greeks, as example.

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    Quote Originally Posted by Barellalee View Post
    23andMe bases these Ancestry Composition origins to least 500 YPB, correct? My Mother is all Italian. Her Maternal Grandparents were from Tuscany, her Paternal Grandmother was from Campania, and her Paternal Grandfather was from Abruzzo. All family surnames were of native Italian and history. On Standard, my X Chromosome is about 90% Italian, nearly 10% Nonspecific Southern European, and a tiny fraction Nonspecific European. In Conservative, it's about 80% Italian, nearly 20% Nonspecific Southern European, and that tiny bit Nonspecific European. In Speculative, it's about 95% Italian. Nearly 5% is now Nonspecific Southern European, and this does not shift into the other References of either Iberian or Balkan, BUT the fraction of Nonspecific European becomes Nonspecific Northern European. Seeing as how the Speculative mode is below a 50% threshold, I really don't believe it's picking up on any genuine North European. Part of the Tuscan side was from the Apuan Alps, and I'm sure getting that far up, it can't be surprising if there is some ancient genetic affinity to say people in Switzerland or France, without there necessarily having to have been North European Admixture. Afterall, the area was once part of Pre-Roman Liguria (Ligures). The fact that the Nonspecific Southern European even below a 50% threshold isn't even hypothetically Iberic nor Balkanic, to me means I don't have genetic similarities to say Spaniards nor Greeks, as example.
    I'm not so sure that 23andMe did the best update in their AC. My Mom's X chromosome doesn't look right. It was more accurate the first time around IMO. I can't even be bothered with Conservative mode there because she has a high percentage of Unassigned. When I view the chromosome painting she is missing two large chunks on her X. I will just comment on Speculative as overall that gives her the best view, but not good on X. The bottom of her X in Speculative is all Italian. On the top half it looks to be 80% Balkan. With finally a little Unspecified Northern European showing. I don't understand it because her father is an Italo-Albanian. Her mother has Colonial roots, with German and Dutch. Something does not add up at all when it comes to the top half of her X.

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    Yes, I would definitely say that doesn't seem right. I guess, my Mother being all ethnic Italian, my X Chromosome is pretty agreeable overall, I mean. Naturally the Arbereshe background you have would account for some Balkan and perhaps some Italian, but DEFINITELY not all that. Which Arbereshe community was the background from?

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    Quote Originally Posted by Barellalee View Post
    Yes, I would definitely say that doesn't seem right. I guess, my Mother being all ethnic Italian, my X Chromosome is pretty agreeable overall, I mean. Naturally the Arbereshe background you have would account for some Balkan and perhaps some Italian, but DEFINITELY not all that. Which Arbereshe community was the background from?
    Yes I would imagine she should have both too. I would think the Balkan and Italian should be mixed together on one side. And if my memory serves me correct that was how her original chromosome painting was from them. The update in one sense seemed to show her father's ancestry pretty good (except on the X). They added Albanians to their Balkan population and her Balkan score did increase overall. When it comes to her mother's side they botched it. The Arbėreshė village her father's family is from is San Nicola dell'Alto.

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    Since having four family members tested at 23andme, we have received some very interesting X chromosome results. Or I should say lack there of that makes them most interesting! My Mom shows as my daughter's grandmother, however they do not match at all on the X! So the one X my daughter received from me came from my father's mother intact! This X chromosome can be traced to two small villages in modern day Slovakia, former Kingdom of Hungary. Maybe 23andme will started using reference pops based on the X. Just kidding, but would be neat to track the X in some way like this. I really can't wait to see how our AC's look when they come out, especially with the X chromosome.

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