Terman, who was a proponent of the notion that IQ was inheritable and who was also associated with the controversial eugenics movement, followed some 1,500 children with high IQs throughout their lives, hoping to correlate IQ with success. Instead, as Gladwell points out, the results of the study show that there appears to be an intelligence threshold for success, but no correlation of degree of success with intelligence beyond that threshold.
In the next chapter, Gladwell focuses on individual cases, showing that what matters is being “smart enough” and that beyond that, IQ points are less important to success than other factors. He chooses as examples Chris Langan and Robert Oppenheimer. While Langan has one of the highest IQs recorded since the test was developed, he was considerably less successful in his life than the distinguished physicist Robert Oppenheimer, who actually had a lower IQ as measured by standardized tests. Gladwell emphasizes that part of the difference between these two men was environment, with Oppenheimer coming from a wealthy family that nurtured his talents and Langan from an impoverished and abusive environment. Gladwell cites work by sociologist Annette Lareau on the differences in parenting styles across the socio-economic spectrum and argues that this is an important factor in the relative success of Oppenheimer and lack of success of