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One of the fun facts about IQ is that it seems to be highly genetic, but not particularly hereditary. There's a .76 correlation for identical twins separated at

One of the fun facts about IQ is that it seems to be highly genetic, but not particularly hereditary. There's a .76 correlation for identical twins separated at a young age, but only .22 between a parent and child, when the child was lived apart from the parent[1]. Compare this to height, which is much more heritable[2]. So they'll probably need more than the 10,000 samples they needed to find height-related genes. It'll be interesting to see the findings. [1]: http://en.wikipedia.org/wiki/Heritability_of_IQ#Correlations_between_IQ_and_degree_of_genetic_relatedness http://en.wikipedia.org/wiki/Heritability_of_IQ#Correlations... [2]: http://en.wikipedia.org/wiki/Twin_study http://en.wikipedia.org/wiki/Twin_study

xaa 14y ago
To me, this suggests that the trait is highly combinatorial, involving potentially large combinations of polymorphisms instead of individual loci acting relatively independently (in an "additive" fashion). Of course, such combinatorial traits are much harder to tease out of data.
goodcanadian 14y ago
There has been plenty of controversy over the meaning of IQ tests in the first place. One complaint is that they test cultural knowledge more than intelligence itself. Naturally, there will be some correlation between the two, but my point is that a great deal of what IQ tests test may be learned knowledge. While your ability to learn that knowledge may be related to intelligence, it does not follow that all intelligent people will score highly on a particular IQ test. Intelligence may be heritable even if IQ test performance is not.