Educational attainment and cognitive competence in adopted men -- A study of international and national adoptees, siblings and a general Swedish population

Internationally and nationally adopted young men were recently reported to have lower than average scores on intelligence tests at military conscription, compared with non-adopted conscripts in Sweden. In this study we used the Swedish national registers to analyse how this lower cognitive competence influences the educational attainment of adoptees. Intelligence test scores at conscription were analysed in relation to educational attainment at follow-up at 25-34 years in male international (n = 2.314) and national (n = 1.153) adoptees, compared with the general population in the same birth cohorts. Korean adoptees more often had obtained a post-secondary education compared with the general population while Non-Korean and national adoptees less often had such an education at follow-up. The international adoptees had a better chance than the general population to complete a post-secondary level and a lower risk to remain at a basic level when their cognitive competence, as measured by intelligence test scores, had been accounted for. This effect was quite similar in biological children in families of international adoptees who had the best test scores, in the Korean adoptees who had slightly better test scores than the general population, and in the Non-Korean adoptees who had considerably lower test scores. National adoptees had similar outcomes in these respects as the general population when test scores had been accounted for. Higher age at adoption was associated with a lower educational attainment in the Non-Korean but not in the Korean adoptees, an effect that was attenuated when test scores were accounted for. We conclude that a lower than average cognitive competence did influence the educational attainment of the Non-Korean international and the Swedish-born adoptees in this study. International but not national adoptees had attained a higher educational level than predicted from their scores on intelligence tests. This education promoting effect was similar in the Korean adoptees, who had high test scores in comparison with the general population, and the Non-Korean adoptees who had comparatively low test scores.