The studies most favorable to Shenk's position put the heritability of IQ at around 0.5. That is, parents account for 50% of their descendant's IQ variance. Env

The studies most favorable to Shenk's position put the heritability of IQ at around 0.5. That is, parents account for 50% of their descendant's IQ variance. Environmental factors would account for the other half. More recent meta-studies (http://www18.homepage.villanova.edu/diego.fernandezduque/Teaching/PhysiologicalPsychology/zCurrDir4200/CurrDirGeneticsTraits.pdf http://www18.homepage.villanova.edu/diego.fernandezduque/Tea... for instance) put IQ heritability at around 0.8. Even if the studies most favorable to Shenk are correct, the best way to be smart is still to choose your parents. Parents determine genes and a large amount of environment, which together are the largest influences on intelligence. This is a bit off-topic, but I want to point out a distinction that is often overlooked. Heritability is not quite the same as genes. Genes definitely influence intelligence. If you could edit someone's genes, you could quite easily make them very sharp or very dumb. Scientists have identified individual genes and groups of genes that drastically influence intelligence. Down's syndrome is an obvious one. Single genes affecting intelligence include GDI1 (http://hmg.oxfordjournals.org/cgi/content/full/11/21/2567 http://hmg.oxfordjournals.org/cgi/content/full/11/21/2567) and ALDH5A1 (http://en.wikipedia.org/wiki/Aldehyde_dehydrogenase_5_family,_member_A1 http://en.wikipedia.org/wiki/Aldehyde_dehydrogenase_5_family...). There are others that cause problems such as autism and schizophrenia. (http://www.nature.com/nature/journal/v455/n7215/full/nature07458.html http://www.nature.com/nature/journal/v455/n7215/full/nature0...) I really think the "ignore genetics, work hard to succeed" people are going about their argument the wrong way. Instead of disregarding the evidence, they should acknowledge it while stressing a caveat: Intelligence, to be useful, must be used effectively. The smartest person in the world might not be best-suited to solve a problem; similar to how the strongest person in the world might not be the best fighter.