>>12196246Research on the heritability of IQ inquires into the proportion of variance in IQ that is attributable to genetic variation within a population. "Heritability", in this sense, is a mathematical estimate that indicates an upper bound on how much of a trait's variation within a population can be attributed to genes.[1] There has been significant controversy in the academic community about the heritability of IQ since research on the issue began in the late nineteenth century.[2] Intelligence in the normal range is a polygenic trait, meaning that it is influenced by more than one gene,[3][4] and in the case of intelligence at least 500 genes.[5] Further, explaining the similarity in IQ of closely related persons requires careful study because environmental factors may be correlated with genetic factors.
Twin studies of adult individuals have found a heritability of IQ between 57% and 73%[6] with the most recent studies showing heritability for IQ as high as 80%[7] IQ goes from being weakly correlated with genetics, for children, to being strongly correlated with genetics for late teens and adults. The heritability of IQ increases with age and reaches an asymptote at 18–20 years of age and continues at that level well into adulthood. This phenomenon is known as the Wilson Effect.[8] However, poor prenatal environment, malnutrition and disease are known to have lifelong deleterious effects.[9][10]
Although IQ differences between individuals have been shown to have a large hereditary component, it does not follow that mean group-level disparities (between-group differences) in IQ necessarily have a genetic basis.[11][12] The current scientific consensus is that there is no evidence for a genetic component behind IQ differences between racial groups.[13][14][15][16][17]
Source: Wiki
