Whether the family context matters for genetic influences on children’s educational attainment remains an open question. Previous research mainly considers parents’ socio-economic standing and overlooks a key dimension of social stratification: childhood family structure. Baier and Van Winkle focus on the extent that parental separation affects genetic influences on educational attainment across 20th Century birth cohorts. The study draws on the US Health and Retirement Study (HRS) to estimate the association between education polygenic scores and educational attainment of adults born across the 20th Century who experienced a parental separation before age 16 compared to adults who lived continuously with both parents. They find that genetic effects are smaller for adults whose parents separated compared to adults whose parents remained coupled. Moreover, the magnitude of genetic effects remained constant across cohorts for adults from two-parent households, but decreased for adults whose parents separated. Additional analyses based on the comparison with adults who lost a parent during childhood indicated that family instability rather than parental absence supresses genetic effects among those whose parents separated. Their findings highlight the importance of socio-historic variation in distinct family conditions linked to parental separation that in turn affect children’s chances to tap their genetic potential for education.