Unfortunately, it's also highly heritable, so environmental interventions have a fairly marginal effect on it. (a) The Flynn Effect demonstrates that IQ is qui

Unfortunately, it's also highly heritable, so environmental interventions have a fairly marginal effect on it. (a) The Flynn Effect demonstrates that IQ is quite responsive to environment. (b) The heritability of a trait is not a measure of the degree to which that trait is genetically determined: Highly heritable traits can be environmently malleable. (The heritability of height is 0.8, but nutrition, childhood sickness, etc. have a huge effect on height.) Conversely, traits with low heritability can be strongly determined, genetically. ("Number of eyes" is a trait with low heritability, for example.) (c) The measured heritability of IQ isn't especially high. It's usually found to be in the vicinity of 0.3.