We employ a three-level model – with siblings nested in families nested in societies – to estimate the variability in family effects on educational attainment across countries and cohorts. To perform this comparative sibling analysis, we use survey data from eleven countries and six time periods. The results first of all show that 34 per cent of the individual variance in educational attainment can be attributed to the family, leaving 37 per cent at the individual sibling level and 28 per cent at the level of the societies investigated. Furthermore, the comparative sibling analysis makes clear that there are significant differences in family effects on educational attainment between countries and cohorts. We find that indicators of modernization, individualization, and socialism negatively influence the measured effects of parents’ socio-economic position on educational attainment. Total family impact does not vary with these societal characteristics in a systematic way, however. This seems to be in line with the reproduction hypothesis, which states that parents use compensating strategies to make up for the loss in effects of parents’ socio-economic position on educational attainment.