In this case I'm assuming that the family has been inbreeding to a level of 2 or closer for a certain amount of generations. Given this what would be the likely issues that would arise after:

  1. Two Generations
  2. Three Generations
  3. Five Generations
  4. Ten Generations

I'm curious to know what kind of effects this would have. Also how would relations be between family members other than the obvious? I'm trying to build this in a world that is currently in its Iron Age.

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    $\begingroup$ You've read about Charles II of Spain, right? $\endgroup$ Commented Mar 24, 2021 at 12:07
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    $\begingroup$ Downvotes without comments are unhelpful, folks, especially for new users. $\endgroup$ Commented Mar 24, 2021 at 12:27
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    $\begingroup$ Curious to hear from the closer about why he believes this is opinion based, the common genetic problems are fairly well documented & studied within reproductive biology & medical science so not a lot of wriggle room for 'opinion' in a reasonable answer I'd have thought. $\endgroup$
    – Pelinore
    Commented Mar 24, 2021 at 12:34
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    $\begingroup$ Insufficient information. It all depends on the stock you started with. $\endgroup$
    – Mary
    Commented Mar 24, 2021 at 12:59
  • $\begingroup$ What genetic problems did Cleopatra VII, the famous queen of Egypt, have? She was a very attractive, very intelligent and very active woman, and she was the last sovereign of the Ptolemaic dynasty, which had practiced inbreeding for some three centuries. Your inbred dynasty may have no genetic problems, or it may have a propensity for, I don't know, catching colds easily. Depends on what story you want to tell: and this is what "primarily opinion based" means. $\endgroup$
    – AlexP
    Commented Mar 24, 2021 at 13:42

1 Answer 1


it would vary how long it could take to see large effects. the major factor would be how far down the family tree is the nearest common ancestor of the two parents. the major effects stay the same, but just get more pronounced over time. These are typically reduced fertility rates and an increase in the likelihood of having genetic diseases.


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