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All real family trees are not tree-shaped but diamond-shaped due to inbreeding (often very distant), a phenomenon geneaologists call "pedigree collapse": https

All real family trees are not tree-shaped but diamond-shaped due to inbreeding (often very distant), a phenomenon geneaologists call "pedigree collapse": https://en.wikipedia.org/wiki/Pedigree_collapse https://en.wikipedia.org/wiki/Pedigree_collapse

P5fRxh5kUvp2th 4y ago
If it's "very distant" is it really inbreeding?
- lofatdairy 4y ago
  It's inbreeding by the technical definition/understanding but obviously it's not inbreeding from a practical/biologically concerning standpoint.
  - P5fRxh5kUvp2th 4y ago
    In that case we're all inbred, so what does the word mean?
    - JumpCrisscross 4y ago
      > we're all inbred, so what does the word mean Genealogically, it means a family tree which is not a binary tree [1]. The measure is meaningful over a certain number of generations. Everyone is inbred over infinite generations, assuming a universal common ancestor. That doesn't sap the term of meaning. Medically, we look at the coefficient of coancestry [2]. Practically, I think we trace back 3 to 4 generations, my source being grandparents (2) is a common word, great grandparents (3) less so but widely understood, and great great grandparents (4) being something few people keep track of. [1] https://en.wikipedia.org/wiki/Binary_tree https://en.wikipedia.org/wiki/Binary_tree [2]https://link.springer.com/referenceworkentry/10.1007/978-1-4020-6754-9_3275 https://link.springer.com/referenceworkentry/10.1007/978-1-4...
    - cactacea 4y ago
      The same thing it always meant. Like many things, just because it's a continuum and not binary doesn't mean it's a useless concept.
      - P5fRxh5kUvp2th 4y ago
        absolutely not. What next, we can defend "tall" being anywhere from 1mm to 9 feet because height is a continuum? Words have meaning so they can be used for communication. If I use the word inbred to mean two siblings having a child and two partners sharing an ancestor 20 generations back, I'm not communicating anything when I use the word inbred. And pointing out that closeness of ancestry is a continuum is not a defense of using that word in that manner.

P5fRxh5kUvp2th 4y ago

If it's "very distant" is it really inbreeding?

lofatdairy 4y ago
It's inbreeding by the technical definition/understanding but obviously it's not inbreeding from a practical/biologically concerning standpoint.
- P5fRxh5kUvp2th 4y ago
  In that case we're all inbred, so what does the word mean?
  - JumpCrisscross 4y ago
    > we're all inbred, so what does the word mean Genealogically, it means a family tree which is not a binary tree [1]. The measure is meaningful over a certain number of generations. Everyone is inbred over infinite generations, assuming a universal common ancestor. That doesn't sap the term of meaning. Medically, we look at the coefficient of coancestry [2]. Practically, I think we trace back 3 to 4 generations, my source being grandparents (2) is a common word, great grandparents (3) less so but widely understood, and great great grandparents (4) being something few people keep track of. [1] https://en.wikipedia.org/wiki/Binary_tree https://en.wikipedia.org/wiki/Binary_tree [2]https://link.springer.com/referenceworkentry/10.1007/978-1-4020-6754-9_3275 https://link.springer.com/referenceworkentry/10.1007/978-1-4...
  - cactacea 4y ago
    The same thing it always meant. Like many things, just because it's a continuum and not binary doesn't mean it's a useless concept.
    - P5fRxh5kUvp2th 4y ago
      absolutely not. What next, we can defend "tall" being anywhere from 1mm to 9 feet because height is a continuum? Words have meaning so they can be used for communication. If I use the word inbred to mean two siblings having a child and two partners sharing an ancestor 20 generations back, I'm not communicating anything when I use the word inbred. And pointing out that closeness of ancestry is a continuum is not a defense of using that word in that manner.