We investigated the heritability of educational attainment and how it differed between birth cohorts and cultural-geographic regions. A classical twin design was applied to pooled data from 28 cohorts representing 16 countries and including 193,518 twins with information on educational attainment at 25 years of age or older. Genetic factors explained the major part of individual differences in educational attainment (heritability: a2 = 0.43; 0.41-0.44), but also environmental variation shared by co-twins was substantial (c2 = 0.31; 0.30-0.33). The proportions of educational variation explained by genetic and shared environmental factors did not differ between Europe, North America and Australia, and East Asia. When restricted to twins 30 years or older to confirm finalized education, the heritability was higher in the older cohorts born in 1900-1949 (a2 = 0.44; 0.41-0.46) than in the later cohorts born in 1950-1989 (a2 = 0.38; 0.36-0.40), with a corresponding lower influence of common environmental factors (c2 = 0.31; 0.29-0.33 and c2 = 0.34; 0.32-0.36, respectively). In conclusion, both genetic and environmental factors shared by co-twins have an important influence on individual differences in educational attainment. The effect of genetic factors on educational attainment has decreased from the cohorts born before to those born after the 1950s.
Silventoinen K, Jelenkovic A, Sund R, Latvala A, Honda C, Inui F, Tomizawa R, Watanabe M, Sakai N, Rebato E, Busjahn A, Tyler J, Hopper JL, Ordoñana JR, Sánchez-Romera JF, Colodro-Conde L, Calais-Ferreira L, Oliveira VC, Ferreira PH, Medda E, Nisticò L, Toccaceli V, Derom CA, Vlietinck RF, Loos RJF, Siribaddana SH, Hotopf M, Sumathipala A, Rijsdijk F, Duncan GE, Buchwald D, Tynelius P, Rasmussen F, Tan Q, Zhang D, Pang Z, Magnusson PKE, Pedersen NL, Dahl Aslan AK, Hwang AE, Mack TM, Krueger RF, McGue M, Pahlen S, Brandt I, Nilsen TS, Harris JR, Martin NG, Medland SE, Montgomery GW, Willemsen G, Bartels M, van Beijsterveldt CEM, Franz CE, Kremen WS, Lyons MJ, Silberg JL, Maes HH, Kandler C, Nelson TL, Whitfield KE, Corley RP, Huibregtse BM, Gatz M, Butler DA, Tarnoki AD, Tarnoki DL, Park HA, Lee J, Lee SJ, Sung J, Yokoyama Y, Sørensen TIA, Boomsma DI, Kaprio J. Genetic and environmental variation in educational attainment: an individual-based analysis of 28 twin cohorts. Sci Rep. 2020 Jul 29;10(1):12681. PMC7391756.