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Heritability of IQ is the term you're looking for. Wiki has a page on it here [1]. The numbers have not been pinned down and it was previously thought to be as

Heritability of IQ is the term you're looking for. Wiki has a page on it here [1]. The numbers have not been pinned down and it was previously thought to be as low as 57%, but recent studies tend to show heritability rates upwards of 80%. There are a lot of complex issues that make study difficult. For instance there's the paradoxical issue that childhood IQ can be somewhat meaningfully influenced by environment, yet that notwithstanding, as children approach adolescence and especially adulthood their IQ becomes ever more a product of genetics. That said environment obviously does play some role, but that role is already a minority player and seems to be getting smaller as we learn more about genetics. [1] - https://en.wikipedia.org/wiki/Heritability_of_IQ https://en.wikipedia.org/wiki/Heritability_of_IQ

bildung 8y ago
From the article: "Heritability measures the proportion of variation in a trait that can be attributed to genes, and not the proportion of a trait caused by genes." If e.g. schools get better, and the whole population would have access to these better schools, everyone would be more intelligent, yet the heritability would still be at 80%.
- TangoTrotFox 8y ago
  You've gotta be careful with Wiki at times. In that same paragraph you'll also see the sentence "Contrary to popular[citation needed] belief, two parents of higher IQ will not necessarily produce offspring of equal or higher intelligence. In fact, according to the concept of regression toward the mean, parents whose IQ is at either extreme are more likely to produce offspring with IQ closer to the mean (or average)." That literally made me laugh. Whoever wrote that has no absolutely clue what regression towards the mean is or means, yet felt qualified to write on it. The reason Wiki is useful is as a collection of sources to meaningful information and statistics. But much of what is written by Wikipedia editors themselves is often very bad, and exponentially more so when you enter into any area that could be in any way controversial -- which includes this topic. It should be taken with a grain of salt. In this case, however, the statement you mention is technically correct. But one thing you have to account for is that 20% encompasses all environmental differences. Put another way, if we all had a 100% identical upbringing and environmental factors then the heritability of any given observation would obviously be 100%, since any deviations from the norm would be primarily due to genetic factors. So that means that all of the wild variations in our upbringings and backgrounds are constrained to as little as 20% of any variation in IQ.

bildung 8y ago

From the article: "Heritability measures the proportion of variation in a trait that can be attributed to genes, and not the proportion of a trait caused by genes." If e.g. schools get better, and the whole population would have access to these better schools, everyone would be more intelligent, yet the heritability would still be at 80%.

TangoTrotFox 8y ago
You've gotta be careful with Wiki at times. In that same paragraph you'll also see the sentence "Contrary to popular[citation needed] belief, two parents of higher IQ will not necessarily produce offspring of equal or higher intelligence. In fact, according to the concept of regression toward the mean, parents whose IQ is at either extreme are more likely to produce offspring with IQ closer to the mean (or average)." That literally made me laugh. Whoever wrote that has no absolutely clue what regression towards the mean is or means, yet felt qualified to write on it. The reason Wiki is useful is as a collection of sources to meaningful information and statistics. But much of what is written by Wikipedia editors themselves is often very bad, and exponentially more so when you enter into any area that could be in any way controversial -- which includes this topic. It should be taken with a grain of salt. In this case, however, the statement you mention is technically correct. But one thing you have to account for is that 20% encompasses all environmental differences. Put another way, if we all had a 100% identical upbringing and environmental factors then the heritability of any given observation would obviously be 100%, since any deviations from the norm would be primarily due to genetic factors. So that means that all of the wild variations in our upbringings and backgrounds are constrained to as little as 20% of any variation in IQ.