I don’t expect to get one definite answer here, but Google can’t give me one either. Some websites say they’re your second cousin, and others say they’re your first cousin once removed. I’m trying to figure out some family tree stuff so I need to know the difference between the (groups of) terms.

  • BlameThePeacock@lemmy.ca
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    1 month ago

    First, Second, Third Cousins have to do with how far up the tree you have to go to find a common ancestor. So someone with the same grandparent as you is your first cousin, someone with the same great grandparent is your second cousin, etc.

    Once, twice, thrice removed is how far down they are in relation to your generation. So if someone is your cousin, and that cousin has a child, they would be the same type of cousin but once removed.

    • JusticeForPorygon@lemmy.worldOP
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      1 month ago

      Thank you for the description, that actually makes it a lot easier to understand.

      So how do you go about combining the two?

      For example, my great grandfather’s sister’s grandson was on the USS Thresher when it imploded. What would his relation be to me?

      On that note, what do you call your grandparent’s sibling, vs your great grandparent’s sibling, and so on? Again, Google isn’t being very helpful here.

      • entropicdrift@lemmy.sdf.org
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        1 month ago

        For example, my great grandfather’s sister’s grandson was on the USS Thresher when it imploded. What would his relation be to me?

        So your first common ancestors are your great great grandparents, so that’s third cousin, and they’re a generation older than you, so once removed. Third cousin once removed. EDIT: This was incorrect, it’s second cousin once removed since that person would be OP’s parent’s second cousin. See the replies below.

        On that note, what do you call your grandparent’s sibling, vs your great grandparent’s sibling, and so on? Again, Google isn’t being very helpful here.

        Grandparents’ siblings are you great aunts/great uncles, additional generations back you add more greats, so great grandparents’ siblings are your great great aunt/uncle. After a while people say “twice great” etc

        • bobagem@sh.itjust.works
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          1 month ago

          So your first common ancestors are your great great grandparents, so that’s third cousin, and they’re a generation older than you, so once removed. Third cousin once removed.

          I believe that the answer is second cousin once removed.

          I believe you need to count the distance to the common ancestor from the older generation of the two people being related.

          I agree that the first common ancestor is OP’s great-great-grandparent. But only OP’s relation’s great-grandparent. So OP’s parent and OP’s relation are second cousins.

          Then the removed takes you down the tree from OP’s parent to OP.

          • entropicdrift@lemmy.sdf.org
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            1 month ago

            Ah, you’re completely right.

            If that person had a kid it’d be your third cousin, but since that person is OP’s parents’ second cousin, they are OP’s second cousin once removed.

      • Nefara@lemmy.world
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        1 month ago

        Your grandmother’s sister is your grandaunt, and you use grand and great the same way you do for mother/father but with aunt/uncle.

        So I think your fourth cousin twice removed was on the Thresher but someone may correct me.

      • Paraneoptera
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        1 month ago

        Great grandfather’s sister’s grandson is your second cousin once removed. That guy is the second cousin of one of your parents because they share great grandparents with one of your parents. A grandparent’s sibling is a great aunt or great uncle to you. A great grandparent’s sibling is a great great uncle or great great aunt to you.

    • AmidFuror@fedia.io
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      1 month ago

      That someone needs to share both grandparents or both great grandparents. Otherwise they are you half first cousin or half second cousin, like you would have half siblings if you shared only one parent with them.

      And then there are double cousins…