Stability and change in the etiology of educational achievement across school years

Individual differences in educational achievement are highly heritable (60%). However, little is known about developmental change and continuity. Here, we study the etiology of educational achievement longitudinally across... [ view full abstract ]

Individual differences in educational achievement are highly heritable (60%). However, little is known about developmental change and continuity. Here, we study the etiology of educational achievement longitudinally across four ages from primary school (age 7) until the end of compulsory education (age 16) using both teacher ratings and exam scores from the UK representative Twins Early Development Study (TEDS) sample (N= 6000 twin pairs). Genetic and environmental estimates were as expected (A~60%, C~20% and E~20%) with little change across the school years or across subjects. Educational achievement is highly stable across all four ages (phenotypic correlations of about 0.70) and this stability is largely (80%) explained by genetic factors, while non-shared environmental factors were mostly (55%) age specific, contributing to change in educational achievement across the school years. About half of the phenotypic stability is explained by intelligence, but the etiology and stability of educational achievement did not change when controlling for intelligence. This pattern was found for overall achievement as well as for specific school subjects. Polygenic score analyses, using years of education (EduYears) summary statistics, indicated that EduYears explained more variance in overall achievement (~9%) compared to specific school subjects (~5%) at the end of the compulsory education. In addition, EduYears explained more variance in later (~9%) compared to earlier school years (~4%).

We conclude that educational achievement throughout the school years is highly stable for all academic subjects and that this stability is driven genetically, even after controlling for intelligence. Educational achievement is an extreme example of the general behavioral genetic rubric of ‘genetic stability, environmental change’. For this reason, adult EduYears predicts educational achievement even in the early school years.