Genes drive most of the link between cognitive ability and socioeconomic status, twin study finds
Mar 10th 2026
A longitudinal twin study led by Petri J. Kajonius finds that shared genetics account for most of the association between cognitive ability in early adulthood and education and occupational outcomes four years later, while noting methodological limits and that heritability is not destiny.
- Study analyzed 440 twin pairs from Germany's TwinLife project, including 228 identical and 212 fraternal same-sex pairs.
- Cognitive ability measured at about age 23 was roughly 75 percent heritable in this sample.
- Genetic factors explained between 49 and 66 percent of differences in educational attainment at age 27.
- Genetics accounted for between 32 and 71 percent of occupational-status differences at age 27.
- Shared genetic effects explained 69 to 81 percent of the association between cognitive ability and education and up to 98 percent of the link with occupational status.
- Authors caution that heritability is not determinism and that the four-year follow-up and simplified gene versus environment models limit conclusions.
- The study does not rule out gene-environment interactions or different long-term career trajectories beyond age 27.