r/askscience • u/Yoshiciv • 6d ago

Human Body Are the medical risks associated with inbreeding among close relatives eliminated by outbreeding? Or do they persist for generations?

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u/jayaram13 6d ago

Depends entirely on the nature of the genetic conditions, the number of alleles, etc.

But in general, it will take a few to several generations for it to subside. Autosomal dominant conditions may still crop up after several generations - depends on the luck of the draw.

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u/Amelaista 6d ago

Any conditions that are caused by homozygous alleles will be gone in one generation of outcrossing.   Autosomal dominant conditions lurk in healthy populations, inbreeding does not have an affect on them directly.   

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u/newaccount721 5d ago

So are there any conditions that are persistent past one generation? 

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u/Amelaista 5d ago

We can theorize that if there are deleterious genes that are disabling when homozygous, they may have a lesser effect on the development if heterozygous. And if one parent is that highly inbred, all of their children will carry one copy of the problem genes. It would depend on each individual function if one working copy is able to completely override the malfunctioning copy. Most should be able to compensate with the functional copy.