This is a sensitive subject, but I am interested in the potential genetic and social impacts it may have had so I'm going to go ahead and post it. Allow me to preface the question by stating that I do not intend this to be a racial, religious, or cultural aspersion - I'm genuinely curious.
I have heard (from unreliable sources) that consanguineous marriage is very common in parts of the Middle East, to the point that a male suitor must ask for and be granted permission by a woman's father's brother's sons before being allowed to marry her. This is known as "bint 'amm marriage"
This sort of arrangement - first cousins - has a relationship coefficient of 0.125 and is therefore under the threshold studied in TFA, and a quick search leads me to believe that it roughly doubles the chance of a serious birth defect. That said, given the strong cultural forces at work here I suspect that many of these unions are in fact between people who are multiply first cousins, which would magnify the effect.
Is anyone here familiar with any studies done on the genetic impact on communities where bint 'amm marriage is practiced?
For reference, here's the Wikipedia article on the practice: en.wikipedia.org/wiki/Cousin_marriage_in_the_Middle_East
Paper claims an conservatively estimated prevalence of 1/3652 for extreme inbreeding which equates to about 18k people, assuming a UK population size of 66 million.
It’s also not always about intentional inbreeding.
Many people don’t know who their biological parents are. While not a significant issue with adoption, if a guy has multiple kids who don’t know their siblings in the same area. Then they are likely geographically close and of similar ages...
And defines this to mean double-first-cousins and closer (perhaps this is standard). Also, as far as I could skim, this is the prevalence today, rather than an estimate of long-run prevalence.
They must surely have data on simple first cousins, but it didn't jump out at me.
For traits, the effect on non-double first cousins can be linearly approximated, which (as far as I know) is a good approximation for inbreeding depression.
For example, taking Fluid Intelligence Score (basically how smart you are), in Table 3, its extrapolated effect size is -3.43, so:
First cousin (relationship coefficient 0.125, inbreeding coefficient 0.0625) would give -0.214 to FIS. To put that in context, for medication, that would be considered a small effect size. So inbreeding at that level is a bit like taking a stupid pill.
Simple first cousins have a coefficient of relationship of 0.125, which is below the threshold considered in the paper.
Received wisdom is that a coefficient below 0.25 doesn't cause serious deleterious effect. I have no idea if that's well supported, but I imagine it's relevant to why it wasn't studied.
The motivating force for this definition is uncles/aunts and closer; it just so happens that double-first-cousins have the same genetic relatedness as double first cousins.
> In this study, we estimated a prevalence of EI of ~1/3652 in individuals of European ancestry born in the UK between 1938 and 1967.
This is enough to explain the contents of Arndale Centres, but even adjusted for the reasons they gave to believe it's too conservative, not enough to explain the Daily Express.
It's hard to gauge without knowing the intricacies of what's being talked about there, but I guess that you're right about the first but not the second.
We Aussies were the original pickpockets and thieves, with plenty of genetic diversity because of our 'common' (ironic) social status, as opposed to the inbreeding gentry. Combine that with the fact that we don't have all that nasty gravity stuff weighing us down because we live upside down, means that of course we look different. Local habitat, such as drop bears, giant wombats, bunyips, snakes and spiders meant that we needed to diversify genetically pretty quickly too!
;-)
Have you seen celebrities from that part of the world? I mainly know comedians. Ricky Gervais, Al Murray, Dara O'Brain... those are all considered normal looking people over there. They'd be considered circus attractions in Australasia. Or speaking of Gervais, compare the cast of the UK office with the cast of the US office. It's night and day. The only person in the UK office who would be considered even average is Tim (Martin Freeman). Martin Freeman is a heart throb by UK standards, but let's be honest - put him in Australia and give him an Aussie accent and no one would look at him twice.
It is funny that you spent so much time in your rant about the English talking about Gervais, who I believe owes his French surname to some ancestry from French Canada.
Well I thought the Norfolk joke that the other poster did was a bit low effort. So I thought I'd go all in and ask the real question - is in-breeding the reason the british and irish often have big weird ugly heads? I am leaning to 'yes'.
Kiwi here, so not biased at all. I'd put it down to better diet and better climate (so more outdoors physical activity), rather than genetic diversity.
"Eschew flamebait. Don't introduce flamewar topics unless you have something genuinely new to say. Avoid unrelated controversies and generic tangents."
ok well, I suppose it was a trite comment and wasn't much use but on the other hand I sort of think it really is pertinent. Lack of Genetic diversity is a problem, I think it's quite easy to understand how Brexit is not likely to improve it, and given the most likely negative outcomes likely to worsen it.
I think many will assume the comment is flame-bait because lack of genetic diversity isn't really a problem. The entire human species had a population less than the current UK for the the majority of its 350,000 yr existence. Most of this time it operated in small related communities where diversity was much lower. Some have hypothesized that the global human population was as low as 2000 individuals for as long as 100,000 yrs. [1]
Perhaps I'm missing it here but I don't see the issue of lack of mobility as the reason. These were not terribly mobile societies, only the wealthiest could afford to travel long distances.
In my small Canadian island province there are small towns in the countryside where people never leave. Work, church, Saturday nights at the legion then repeat.
I recall a story of a person who was refused gas at a rural gas station because they were not from the area. In a another town a motel refused Coast Guard workers a room because they weren't from the town.
Coast Guard workers who were going home when their shift was over (28 days on and 28 off). The ship docked at the wharf in the small seaside town when patrolling in the area. The ship was leaving and they were waiting for a drive home but had to stay overnight. My dad worked on the same ship and they told him the story later.
No that's just re-stating who they didn't rent to. I mean who did the motel rent rooms to? Only people in the town? Why would they be renting rooms? It doesn’t make any sense.
Yes it's weird. I think everyone involved had those same questions.
I got the story directly from my father who worked with the guys. It could have been bigotry maybe the men refused service were denied due to their appearance, accent, job (fishermen upset with Coast Guard workers).
My aunt was refused a hotel room in Quebec City because she is English. Her French husband asked and was told sure no problem but the clerk said to him in French "let me get rid of this English pig fisrt". My aunt spoke French ( awkward!). That was a story often told at family reunions.
Sure! But "only the wealthiest could afford to travel long distances" is over the top. It's not some sample from before the bicycle. These people's parents, or grandparents, were mixed up all over the planet in WWII.
It would be interesting to know more details about this 0.03 percent. No idea whether you should put your money on small towns or on big cities (e.g. parents both adopted & didn't know).
My (late) German cousin told me about a friend of his Swabian wife’s who moved to Swabia from her native Berlin and went to the bakery asking for Brötchen. She was told to come back when she learned how to speak German. (Maybe she said Schrippe by mistake?)
This one of the main gripes I have with living in Austria and Germany.
In places that are not touristic or in smaller cities that are not a big metro areas, speaking German (Hochdeutsch) is not enough. Failure to speak the local dialect of that region will get you ridiculed or even discriminated against. Not just in the service industry, but in job hunting as well.
My old workplace bought parts from a company in Graz, Austria occasionally they sent technicians over here to Canada. I had been practicing some German using Duolingo. At lunch I used a phrase and the Austrian guy told me how to say it in Austrian. It was funny more of a humorous jab at German pronounciation. My impression was the Austrian guys were really laid back.
From Kiev to Brest is ~3,000km. You’d only need to walk 34km a day to do that in a summer. Walking is cheap and Britain is a fair bit smaller than Europe. At the same pace you can walk the length of Britain in under a month.
I have heard (from unreliable sources) that consanguineous marriage is very common in parts of the Middle East, to the point that a male suitor must ask for and be granted permission by a woman's father's brother's sons before being allowed to marry her. This is known as "bint 'amm marriage"
This sort of arrangement - first cousins - has a relationship coefficient of 0.125 and is therefore under the threshold studied in TFA, and a quick search leads me to believe that it roughly doubles the chance of a serious birth defect. That said, given the strong cultural forces at work here I suspect that many of these unions are in fact between people who are multiply first cousins, which would magnify the effect.
Is anyone here familiar with any studies done on the genetic impact on communities where bint 'amm marriage is practiced?
For reference, here's the Wikipedia article on the practice: en.wikipedia.org/wiki/Cousin_marriage_in_the_Middle_East