Do note that in the study sample only 4 females and 2 males among parents attended secondary school, the rest didn’t have any education beyond elementary school (out of 141 mothers and 138 fathers).
Poor countries are like that. The people in the Indian studies and elsewhere won’t be too highly educated either.
So if you select a population which engages in incest, you are co-selecting for low IQ and so for a larger proportion of bad-for-IQ genes. And the larger that proportion, the worse are the chances (growing superlinearly, too) for the child to have normal IQ.
Shouldn’t affect within-population comparisons… Although since prevalence of cousin-marriage differs drastically from country to country, the inbreeding effect could be driving a nontrivial amount of between-population differences in intelligence. (And of course, it’s not like intelligence is unrelated to national wealth either.)
This is Europe, though, and Communist governments tend to be big on education.
Shouldn’t affect within-population comparisons.
Within which population? The control group involves one parent “from the outside”, so regression to the mean kicks in and the chance of the recessives finding a pair falls dramatically.
I am not arguing that incest has no significant consequences. I am arguing that if you take children of incestuous unions where both parents have reasonable IQ (say, >85), the mean IQ of children would NOT drop by 28 points.
This is Europe, though, and Communist governments tend to be big on education.
It is one of the poorest parts of Europe, and Communist governments tended to be big on a lot of things they couldn’t deliver.
Within which population? The control group involves one parent “from the outside”, so regression to the mean kicks in and the chance of the recessives finding a pair falls dramatically.
If you’re comparing within an Indian population, then the much higher rates of inbreeding aren’t the confound; all you have is the remaining selection effect, and that’s must be small because anything else would drastically contradict the animal and other breeding experiments, and the estimates from genomic methods.
I am arguing that if you take children of incestuous unions where both parents have reasonable IQ (say, >85), the mean IQ of children would NOT drop by 28 points.
It would probably drop by more like 25 points, looking at the weighted averages. (For the surviving children, that is.)
It is one of the poorest parts of Europe, and Communist governments tended to be big on a lot of things they couldn’t deliver.
Communist governments delivered on that one.
Take a look here, specifically pages 21 and 23. The secondary education in Eastern Europe was more prevalent than in Mediterranean countries and Great Britain + Ireland (but less than in Nordic countries and Central Europe). And Czechoslovakia was one of the better Eastern European countries.
If you’re comparing within an Indian population
I went and looked at the Jammu & Kashmir study and it is more convincing than the Czechoslovak study. Hm. It seems my scepticism about the 20+ IQ points drop was unfounded, changing my mind… :-)
But why did my intuition didn’t like the large magnitude of IQ drop? I think because it implies that intelligence is very fragile and very easy to genetically screw up. But if the IQ drop is valid, then intelligence is very fragile. Hmm...
Poor countries are like that. The people in the Indian studies and elsewhere won’t be too highly educated either.
Shouldn’t affect within-population comparisons… Although since prevalence of cousin-marriage differs drastically from country to country, the inbreeding effect could be driving a nontrivial amount of between-population differences in intelligence. (And of course, it’s not like intelligence is unrelated to national wealth either.)
This is Europe, though, and Communist governments tend to be big on education.
Within which population? The control group involves one parent “from the outside”, so regression to the mean kicks in and the chance of the recessives finding a pair falls dramatically.
I am not arguing that incest has no significant consequences. I am arguing that if you take children of incestuous unions where both parents have reasonable IQ (say, >85), the mean IQ of children would NOT drop by 28 points.
It is one of the poorest parts of Europe, and Communist governments tended to be big on a lot of things they couldn’t deliver.
If you’re comparing within an Indian population, then the much higher rates of inbreeding aren’t the confound; all you have is the remaining selection effect, and that’s must be small because anything else would drastically contradict the animal and other breeding experiments, and the estimates from genomic methods.
It would probably drop by more like 25 points, looking at the weighted averages. (For the surviving children, that is.)
Communist governments delivered on that one.
Take a look here, specifically pages 21 and 23. The secondary education in Eastern Europe was more prevalent than in Mediterranean countries and Great Britain + Ireland (but less than in Nordic countries and Central Europe). And Czechoslovakia was one of the better Eastern European countries.
I went and looked at the Jammu & Kashmir study and it is more convincing than the Czechoslovak study. Hm. It seems my scepticism about the 20+ IQ points drop was unfounded, changing my mind… :-)
But why did my intuition didn’t like the large magnitude of IQ drop? I think because it implies that intelligence is very fragile and very easy to genetically screw up. But if the IQ drop is valid, then intelligence is very fragile. Hmm...