Variance in educational attainment in Minnesota by 24 years of age as a function of IQ (in standard deviation units) measured at 17 years of age. Results are shown for three sources of variance: genetic (A), shared environmental (C), and nonshared environmental (E) influences. We observed less genetic variance in educational attainment across the intelligence range in the MTFS population than in the Swedish population. For example, Table 3 shows that at the mean level of intelligence, genetic variance was .35 in the MTFS group, but .50 in the Swedish group. Genetic variance in educational attainment increased across the range of intelligence in both samples. The increase was steeper in the MTFS population than in the Sweden population: It quadrupled from .16 to .64 across the 4-standard-deviation range of intelligence in the MTFS population, but slightly more than doubled in the Swedish population.