[ANON POST] Effect of Inbreeding in Humans

Sep 02, 2012 12:46

Hello, I'm writing a story that takes place in a post-apocalyptic future in a not-specsific east coast city.

trigger warning for incest )

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elaiel September 2 2012, 16:56:05 UTC
She's likely to be fine. Inbreeding is usually only a significant issue cumulatively. Unless the parents are carriers for a genetic disorder it's likely the child won't have any problems from the incest.

No idea about the cancer.

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marycatelli September 2 2012, 17:03:19 UTC
Any genetic problem. Mind you, it's something like a 20% chance of such problem, given that it's a one-time thing, but the problems will depend entirely on what sort of deletrious genes you start with.

For instance, among the Amish, where you don't marry first cousins, but second cousin marriages are common, and one researcher even found a couple who were quadruple second cousins (plus several triple second cousin, a lot of double second cousins, and scads of second cousins) dwarfism is quite common. On a Pacific island where, researchers suspect, the entire population was once reduced to a handful by a typhoon, achromitism is quite common. (Color-blindness - and the sort of colorblindness that you would immediately think of on first hearing the term.)

So pick a genetic problem quite common in their ancestral populations and give the kid it.

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taselby September 2 2012, 17:14:01 UTC
Really, the odds are that the baby will be just fine. If you *want* a specific defect, you can, of course, write that in, but if both of the parents are healthy (cancer aside) and there are no recessive genetic anomalies lurking in the family tree (polydactyly, hemophilia, albinism, tay-sachs, sickle-cell, cystic fibrosis, etc -- http://en.wikipedia.org/wiki/Genetic_disorder), then the baby is like to be fine and of normal intelligence.

If Dad had an X-linked disorder AND Mom was a carrier, then the baby does have a 50% chance of having that disorder as well. At the minimum, she would be a carrier (getting the flawed X chromosome from Dad).

If Dad's cancer is environmental, then baby would possibly be exposed to the same environmental carcinogens as Dad. Age of the parents might cause a difficult pregnancy and birth, since Mom doesn't sound like she's finished developing yet, herself.

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punch September 2 2012, 17:20:06 UTC
Generally their child would be fine. There are lots of cases you can google about siblings who were split up at birth, and ended up having kids.

The way it works is: the chance of having genetic diseases (if there are any in the family, of course) are doubled, because both sets of chromosomes are coming from the same gene pool. Especially if the disease is carried on through the dominant allele.

I've also read somewhere that there's an increased chance of down syndrome, but I could be wrong.

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clarice September 2 2012, 17:25:29 UTC
With a single instance of sibling inbreeding, it would be plausible for the child to have normal intelligence and no deformities or disabilities. Inbreeding increases the odds of inheriting two recessive alleles, but the rate of birth defects and genetic disease is not 100%. Close inbreeding is risky, but it becomes a serious problem when you have multi-generational close inbreeding, which produces Charles Habsburg. The first generation is a bit of a coin flip ( ... )

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parmalokwen September 2 2012, 17:48:46 UTC
Very apt choice of icon.

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swan_tower September 3 2012, 07:41:43 UTC
which produces Charles Habsburg

I heart this line, and you for knowing about him. :-)

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