In this study, we estimate trends in family background effects on educational attainment for the former Federal Republic of Germany (FRG), the former German Democratic Republic (GDR), and the Netherlands. To this end, we employ data on siblings born between 1920 and 1970. This enables us to test hypotheses derived from modernization theory and political theory. We find that the total family impact, which is defined as sibling resemblance in educational attainment, does not show a systematic pattern over time in the former FRG. Effects of father's and mother's educational attainment decrease, however. In the former GDR, the unmeasured part of total family impact follows a U-shape over time, whereas effects of parental education decline. This means that other aspects of the family gained in importance for cohorts born around 1950 and 1960. Additional analyses show that parents' political party membership is not one of these aspects. Finally, in the Netherlands, the effects of traditional indicators of parental social class decrease over time. The declining trend in total family impact on educational attainment appears not to be significant.