Sunday, December 06, 2009

Post on the Genetics of Intelligence

I found this on Dissecting Leftism. Key Ideas are highlighted.

Original Source:

It is obvious that life experiences have some influences on us. Chinese kids grow up speaking Chinese, for instance. But genetics are also powerful and the latest research indicates that they do to a remarkable extent overwhelm environmental influences. Environmental handicaps tend to fade in importance as we get older. Abstract of the latest paper on the heritability of IQ below:

The heritability of general cognitive ability increases linearly from childhood to young adulthoodBy C M A Haworth et al.

Although common sense suggests that environmental influences increasingly account for individual differences in behavior as experiences accumulate during the course of life, this hypothesis has not previously been tested, in part because of the large sample sizes needed for an adequately powered analysis. Here we show for general cognitive ability that, to the contrary, genetic influence increases with age. The heritability of general cognitive ability increases significantly and linearly from 41% in childhood (9 years) to 55% in adolescence (12 years) and to 66% in young adulthood (17 years) in a sample of 11 000 pairs of twins from four countries, a larger sample than all previous studies combined. In addition to its far-reaching implications for neuroscience and molecular genetics, this finding suggests new ways of thinking about the interface between nature and nurture during the school years. Why, despite life's 'slings and arrows of outrageous fortune', do genetically driven differences increasingly account for differences in general cognitive ability? We suggest that the answer lies with genotype–environment correlation: as children grow up, they increasingly select, modify and even create their own experiences in part based on their genetic propensities.
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