In his interview with Crowder, Sowell made at least four points I thought were interesting related to IQ, showing IQ to be more nurture and less genetic than previously thought:
- The first-born child has higher IQ than a later born child.
- The only child has a higher IQ than the average first-born child.
- Twins have lower IQ than singly-born children on average.
- In cases where twins were conceived but one child was stillborn, the surviving twin has, on average, an IQ non-distinguished from singly-born children.
He also made one non-surprising claim, but it’s still an important basic point. IQ is correlated with socioeconomic status, but it’s not without caveats. In one study, thousands of individuals with 140+ IQ failed to receive a Nobel while a person with IQ under that threshold obtained a Nobel. Sowell didn’t say it but the common moral is that conscientiousness, grit, and similar traits matter as well. Such traits matter on average and they may matter heavily at the higher ends of the distribution of achievement.