Barring specific diseases like Marfan Syndrome, we can't yet explain most of height -- "Height is a highly heritable trait, with estimates of heritability as hi

Barring specific diseases like Marfan Syndrome, we can't yet explain most of height -- "Height is a highly heritable trait, with estimates of heritability as high as 90%. Recent genome-wide association studies of height have discovered over 180 common variants associated with height. These variants have small effect sizes and collectively explain approximately 10% of the heritability." [1] Growth involves many systems with many types of cells interacting -- digestive, skeletal, endocrine, etc. There's a lot of complexity when you have so many systems involved. By comparison, there are relatively few distinct types of cells in the brain, so the effects of different alleles should be more apparent. In particular, genes controlling sensitivity to and production of neurotransmitters directly impact brain function. If they find many specific mutations that cause better performance on specific tasks (working memory, pattern matching, verbal ability, ...) it should be possible to predict high IQs. I don't expect 100% accurate predictions, but to not find _anything_ would be surprising. Maybe that's your point-- if they only get 10% heritability, it's not really enough for breeding decisions. [1] http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1002439 http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fj...