Heritability of body height and educational attainment in an international context: Comparison of adult twins in Minnesota and Finland

We studied the effect of genetic and environmental factors on the association between self-reported height and education in Minnesota and Finland. Our data included 1,598 twin pairs in Minnesota and 5,454 twin pairs in Finland born between 1936 and 1955. Correlations between education and height were found in Minnesota (r = 0.09 in men and 0.11 in women) and in Finland (r = 0.17 and 0.14, respectively) after adjustment for age. This trait correlation was mainly because of the correlation between shared environmental factors in Minnesota (r_C = 0.38 and 0.36, respectively) and in Finland (r_C - 0.74 and 0.37, respectively). An unshared environmental correlation was found only in Finland (r_E = 0.13 and 0.06, respectively). Our results indicate that the association between body height and education is overwhelmingly due to the correlation of the shared environmental factors affecting these two traits. The differences between Minnesota and Finland are possibly associated with average higher education in Minnesota, which decreases the effect of the childhood environment on education, seen as a weaker correlation between height and education. Nonfamilial factors affecting education are possibly different in Minnesota than in Finland, since in Finland they are partly associated with the factors affecting height.