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Thread: Does 23andMe's Timeline feature corroborate between family members using 23andMe 🤔

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    Does 23andMe's Timeline feature corroborate between family members using 23andMe 🤔

    Has anyone noticed if the timeline feature corroborates between family members 🤔
    For instance will an uncle's and nephews results be a generation different amongst an ancestor they share amongst that ethnicity etc respectively 🤔

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    It doesn't necessarily correlate. It depends on whether a given ancestry was inherited from just one parent, or both.

    For example, the highest percentage 23andMe shows for me is 43.5% British & Irish, so they say

    You most likely had a parent, grandparent, or great-grandparent who was 100% British & Irish. This person was likely born between 1870 and 1930.

    However, my dad's percentage isn't all that much different from mine: 45.0%. So they tell him

    You most likely had a parent, grandparent, or great-grandparent who was 100% British & Irish. This person was likely born between 1840 and 1900.

    The only thing different is the years, since they're based on when my dad and I were born. As you can see, it's still "parent, grandparent, or great-grandparent for both of us." Conceivably, I inherited most of my father's British & Irish, rather than just half of it; but more likely, I simply inherited British & Irish from both parents.

    Certainly this is true for my daughter, since she actually has more British & Irish than I do: 59.0%. So in her timeline you'd see this

    You most likely had a parent, or grandparent who was 100% British & Irish. This person was likely born between 1930 and 1960.

    Not only are the years different, since Kathryn is a generation younger than I am, but for her the prediction doesn't go past grandparent. This wouldn't have to mean one of my parents -- and obviously it can't be my father, since we can see he's only 45.0% British & Irish. It could be my mother, though it isn't.

    Or my daughter's "100%" British & Irish parent or grandparent could mean either her mother or one of her mother's parents. Only, it doesn't. Here is my wife's British & Irish: 66.8%.

    So 23andMe tells Diane

    You most likely had a parent, or grandparent who was 100% British & Irish. This person was likely born between 1900 and 1930.

    Notice that, except for the years, that's exactly the same prediction as for Kathryn. The reason is that Kathryn inherited more British & Irish from her mother than she did from me, so she has more of this component than I do; but at the same time she did inherit the component from both parents.

    This points up a flaw in 23andMe's reasoning in its timeline. They assume that each given ancestry can be traced to just one "most recent ancestor" who's 100% of that ancestry. For many of their customers -- perhaps even for most of the American ones -- this will not always be true.

    On the other hand, I can also show you an ancestry that my daughter inherited only from me. It's a very small amount of Native American. For me, the percentage is 2.0%, and 23andMe says

    You most likely had a fourth great-grandparent, fifth great-grandparent, sixth great-grandparent, or seventh great (or greater) grandparent who was 100% Native American. This person was likely born between 1690 and 1780.

    And for my daughter, who has 1.5%, 23andMe says

    You most likely had a fourth great-grandparent, fifth great-grandparent, sixth great-grandparent, or seventh great (or greater) grandparent who was 100% Native American. This person was likely born between 1720 and 1810.

    Huh. That's the same prediction as for me, except for the years. So in this case, the problem isn't that Kathryn inherited this ancestry from both parents, but that she inherited much more than half the amount of Native American DNA that was passed on to me.

    That shows a 2nd flaw in 23andMe's reasoning, that you can assume that you inherited half of any given ancestry each parent has. That certainly is not always true, especially for a component that is pretty small to begin with. You might not inherit any of it; you might inherit all of it. Or anything in-between.

    However, for a larger ancestry -- as long as you inherited from just one parent -- it likely will correlate as to both the years and the number of generations back that the "100%" ancestor is predicted to have lived. Not always, but more often than not.
    Besides British-German-Catalan, ancestry includes smaller amounts of French, Irish, Swiss, Choctaw & possibly Catawba. Avatar picture is: my father, his father, & his father's father; baby is my eldest brother.

    GB

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    Interesting... when they say back to an ancestor of 100% of that ethnicity Are you sure they mean to literally 100% as I don't think anyone is 100% of an ethinicty🤔
    Example an typical Italian is 70% Italian DNA the rest made up of admix a typical Irish person is 95% Irish DNA the rest admix.. and typical British person is 60% British DNA the rest admix so if they are only taking it back to the most recent ancestor that had the percentages of a typical native to that country does that change things at all for the math you mention for your family above and how things could be perceived for Kathryn 🤔

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    Quote Originally Posted by Claudio View Post
    Interesting... when they say back to an ancestor of 100% of that ethnicity Are you sure they mean to literally 100% as I don't think anyone is 100% of an ethinicty��
    Example an typical Italian is 70% Italian DNA the rest made up of admix a typical Irish person is 95% Irish DNA the rest admix.. and typical British person is 60% British DNA the rest admix so if they are only taking it back to the most recent ancestor that had the percentages of a typical native to that country does that change things at all for the math you mention for your family above and how things could be perceived for Kathryn ��
    You're probably right that no one is really 100% of anything, except that at 23andMe if someone is part of the reference population for a particular group, they'll be 100% by definition. Those that aren't, will be excluded from the group.

    At Ancestry, for any ancestral component you can see how a "typical native" compares. For example, I have 44% Europe West. But, the average "Europe West" for a typical native of the region isn't much higher -- just 44%.

    In the case of 23andMe, they really do seem to mean to show your ancestry timeline going back to individuals with 100% of whatever component is being considered. It may very well be that you're right about the reality, and in many cases you'll never find the ancestor who was 100%.
    Besides British-German-Catalan, ancestry includes smaller amounts of French, Irish, Swiss, Choctaw & possibly Catawba. Avatar picture is: my father, his father, & his father's father; baby is my eldest brother.

    GB

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    What was your oldest ancestor on your 23andMe timeline.. and how accurate do you think the 23andMe timeline Was for them? What do you think the margin of error is? 100 years? More? Less?

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    Nope, it's all over the place for those of us in the family that took it. I don't really pay much attention to it because of that, but it'd be nice if they could get it straight for the amount we paid!

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    Quote Originally Posted by serena297 View Post
    Nope, it's all over the place for those of us in the family that took it. I don't really pay much attention to it because of that, but it'd be nice if they could get it straight for the amount we paid!
    Got my results..
    23andme gave me Italian,British,and Jewish ancestry and to a much smaller extent French and German,Iberian and Scandinavian.
    I only have a paper trail for the Italian,British and Jewish but the timeline surprisingly matches the paperwork.. I expect the further back it goes the less accurate it gets lol

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    That's exciting! It probably does get less accurate the farther back you go. Plus, I always assume at least some of it is noise depending on how little of a percentage it is. Those of us without a paper trail have less to work with I guess, so it's amazing it lines up for you!

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    Quote Originally Posted by serena297 View Post
    That's exciting! It probably does get less accurate the farther back you go. Plus, I always assume at least some of it is noise depending on how little of a percentage it is. Those of us without a paper trail have less to work with I guess, so it's amazing it lines up for you!
    As far as you know/been told,what is your known ancestry?
    What did 23andMe give you?
    How does it compare?

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    As far as I know I'm Punjabi. Everyone has their family stories of coming from here or there, but I just expected Indian tbh. 23andme gave me mainly South Asian, random bits of Finnish and European. Yet at conservative it was only sure 80 something percent was SA which was odd for me. Wasn't aware that 23 lumped together South Asian with Central Asian either so it wasn't til I transferred to other sites that I saw I was roughly half Indian half CA. It's all cool, but I don't have much to validate it with and I'm skeptical about everything lol. I think in terms of Euro genetics most people find it matches up with what they know or found through research. The rest of us it's kind of hit or miss and we have to spend extra time figuring it all out. Guess I sorta signed up for it though lol.

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