It's happening among the Amish. Johns Hopkins has been studying genetic abnormalities among the Amish for at least a decade.

Anonymous wrote:One blue and one brown or green eye.

That's only in X-men not cousins.

One blue and one brown or green eye.

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:Any medical professionals out there? What is the effect on offspring, if first cousins keep producing children, generation after generation. Does this do something to their brain?

Inbreeding doubles the risk of birth defects and can trigger latent, recessive genes with regards to rare medical conditions.

For example, the fundamentalist Mormons have terribly high rates of a specific mental retardation that is very, very rare among the general population.

But that's mostly a founder effect, as I understand.

The Amish have very rare (and bad) genetic conditions. According to a quick search, it looks like they don't marry cousins or even second cousins, but the problem stems from the original small founders group that was very small and isolated and the genes traveled down the lines. I'd be interested if anyone happens to know more about this.

Isn't that what the Punnett Square is for to help try to determine:

https://en.wikipedia.org/wiki/Punnett_square

I actually don't remember the details about how the Punnett Square works. But I think it's like other posters already described. Where if you have people with similar genes keep reproducing, the chances of a recessive gene become dominant becomes greater.

I think I read somewhere that this was an issue with dog breeding when trying to produce pure bred dogs. Where eventually some dogs get those genetic defects due to staying within their own pool.

Somebody may have to correct what I said above. My memory on this is fuzzy. This was probably from college or high school Biology and it's not like I did well or understood those classes anyways.

Anonymous wrote:

Anonymous wrote:Any medical professionals out there? What is the effect on offspring, if first cousins keep producing children, generation after generation. Does this do something to their brain?

Inbreeding doubles the risk of birth defects and can trigger latent, recessive genes with regards to rare medical conditions.

For example, the fundamentalist Mormons have terribly high rates of a specific mental retardation that is very, very rare among the general population.

I think in a lot of middle eastern countries marrying your first cousin is actually preferred, because people do not want to deal with outsiders. But it's not like every single family member will marry a first cousin or a relative, and a lot of people marry distant relatives like second or third cousins. This was common all over the world (Downton Abbey!). In my family, there are a few medical conditions that appear in several family members that maybe would not occur if people in the previous generations had married out of the family, like epilepsy and some eye conditions. But we don't seem much more diseased than other people otherwise. There are a lot of educated and physically attractive people in my family so it's not like the effects are obvious.

Look up the Pakistani population in the UK.

We get Millenials.

Saudi Arabia, high incidence of inherited conditions.

Anonymous wrote:Any medical professionals out there? What is the effect on offspring, if first cousins keep producing children, generation after generation. Does this do something to their brain?

Inbreeding doubles the risk of birth defects and can trigger latent, recessive genes with regards to rare medical conditions.

Omg how have I never heard of the blue people before? Fascinating

Anonymous wrote:Look up the pharaohs of Egypt. Lots of inbreeding there.

But the pharaohs married siblings (one-half of the genes in common, on average) not first cousins (one-eighth of the genes in common, on average).