• yesman@lemmy.world
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    23 hours ago

    Ancestry is weird. You’ve got 2 parents, 4 grandparents and so on. Do the math and you’ll have a billion ancestors in like 40 generations. Obviously, we can’t all have a billion unique ancestors, so mathematically there must be plenty of people in my family tree that are also in yours. No matter the geographic spread or race nonsense.

    However it’s also true that you’ve got 50% of your parents DNA, ~25% grandparents and so on. Which means eventually, you’ll have an ancestor that you share no genetic markers with. It’s usually about generation 12 where this happens.

    So it’s true that we’re all related and it’s also true that your not related to your 12th great grandfather.

    • bluGill@fedia.io
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      23 hours ago

      As you get back more than 12 generations it is highly likely the same person appears more than once in your family tree.

        • bluGill@fedia.io
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          22 hours ago

          3 generations for rednecks… Cousin marriage is often legal and not unheard of, though most people try to avoid such close relatives. By 3rd cousins - 5 generations - you often don’t even know everyone and so it wouldn’t be a surprise if you don’t even know you are so closely related until long after you have kids. Generally there is enough separation that this isn’t a genetic issue. Even first cousins don’t typically share enough genes for issues to be much more common than otherwise. (kids of brothers-sister pairs often have genetic issues).

      • bluGill@fedia.io
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        19 hours ago

        Even that changes. My surname is what it is because English doesn’t have the same accents of the old German script (which isn’t used in Germany anymore), and so the spelling changed. Then over time how we pronounce it has changed to match the spelling.

        • Mac@mander.xyz
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          13 hours ago

          Mine also changed a few generations ago. Not drastically, but still.