However, numerous twin and adoption studies suggest IQ is heritable.
Various studies have found the heritability of IQ to be between 0.7 and 0.8 in adults and 0.45 in childhood in the United States. It may seem reasonable to expect that genetic influences on traits like IQ should become less important as one gains experiences with age. However, that the opposite occurs is well documented. Heritability measures in infancy are as low as 0.2, around 0.4 in middle childhood, and as high as 0.8 in adulthood. One proposed explanation is that people with different genes tend to seek out different environments that reinforce the effects of those genes. The brain undergoes morphological changes in development which suggests that age-related physical changes could also contribute to this effect.
A 1994 article in Behavior Genetics based on a study of Swedish identical/fraternal twins found the heritability of the sample to be as high as 0.80 in general cognitive ability, however it also varies based on the trait, with 0.60 for verbal tests, 0.50 for spatial and speed-of-processing tests, and only 0.40 for memory tests; in contrast, studies of other populations estimate an average heritability of 0.50 for general cognitive ability.
In 2006, The New York Times Magazine listed about three quarters as a figure held by the majority of studies.
Few would argue that IQ is 100% biological, but biology probably plays a bigger role than environment.
And because I don’t feel like rewriting everything, to quote an earlier essay Does the Nation Make the Genius?
Yes, social factors play a role, but I think genes are more important, especially now that the Flynn Effect seems to be diminishing or reversing, which is evidence the playing field has been leveled. With food abundant and excessively generous welfare and education spending, environmental factors can no long be blamed as much for the differences between individual socioeconomic outcomes. Also, research by Jensen, Herrnstein, Murray, and Rushton shows that IQ tests are not culturally biased and that negative environmental factors (being born into poverty) does not preclude upward mobility for high-IQ individuals. Of course, even in the most optimal of conditions, few geniuses will ever attain the greatness of Shakespeare, but the arts, to a large degree, are subjective. Being a genius in terms of IQ may help one grasp abstract physics and mathematics concepts quickly, even if one doesn’t become the next Einstein*.
To to address the video, many on the left assume IQ is meaningless because not every high-IQ person accomplishes a lot, or that IQ is poor measure of creativity. However, the evidence suggest otherwise, from In Defense of Smart People:
According to a well-received TedX talk Do standardized tests matter?, people with high SAT scores (a good proxy for IQ) do better in life as measured by academic achievement, creative output, job performance, and income. Although the odds of finding the next Elon Musk or Mark Zuckerberg in the high-IQ subset of the population are low, it’s pretty much zero in the modest IQ subset. Billionaires, in general, are much smarter than everyone else, and while not every high-IQ person will become rich, having a high-IQ certainly helps.
Here is the TedX talk which demolishes the belief that IQ (and its proxy the SAT) is not predictive of creativity.
So while not every >130 IQ person will become the next Einstein, his odds are much higher than someone with an IQ <100. IQ measures the potential to succeed and or be creative, not actual creativity or success itself. It just so happens this number called 'IQ' does a pretty good job at measuring skills (or the ability to acquire said skills) that are pertinent to success in society. IQ is a subject that, predictably, makes many uncomfortable because it challenges their belief (ingrained by pop culture, school, parents, teachers, etc) that they have complete control and free will:
Of course, there are many kinds of talent, many kinds of mental ability and many other aspects of personality and character that influence a person’s chances of happiness and success. The functional importance of general mental ability in everyday life, however, means that without onerous restrictions on individual liberty, differences in mental competence are likely to result in social inequality. This gulf between equal opportunity and equal outcomes is perhaps what pains Americans most about the subject of intelligence. The public intuitively knows what is at stake: when asked to rank personal qualities in order of desirability, people put intelligence second only to good health. But with a more realistic approach to the intellectual differences between people, society could better accommodate these differences and minimize the inequalities they create.
Source: The General Intelligence Factor
We want to believe we can achieve or do anything, or (for the left) that the state can help pull people up, but the biology renders efforts to create equality futile.
Thomas Sowell on The Bell Curve
IQ and Morality; IQ and Job Performance
— Bullycide Technician (@KawaiiKraken) February 10, 2015