“…If, for instance, highly educated parents are less likely to divorce and do so only when there is a very high degree of conflict in the relationship, then their children might be selected on negative unobserved characteristics that might also explain their larger penalty in educational attainment. To complicate matters further, the educational gradient has changed over time from positive to negative, making it difficult to predict the implications for the potential biases due to selection into divorce in a cross-cohort study like this one (Bernardi and Martínez Pastor 2011;Härkönen and Dronkers 2006;Matysiak, Styrc, and Vignoli 2011). These concluding observations suggest the need for additional research on the social background gradient in the divorce penalty which draws on more information about the social background of both parents, and which is based on research designs that permit the analysis of the endogenous nature of divorce when studying its consequences.…”