2 EMPIRICAL EVIDENCE Twin and adoption studies have been used to disentangle the intergenerational transmission mechanism (Hübler, 2018). In the former case, outcomes of children born to identical twin sisters can be analysed net of any genetic influences, but this requires a strong assumption that twins are identical except for the outcome of interest. Furthermore, the father's unobservable characteristics are not controlled for, nor is the bias from assortative mating (Dickson et al., 2016).
