Two lives, three legs, one journey: a retrospective appreciation of Zena Stein and Mervyn Susser

‘The proponents of a genetic cause of the unequal distribution of intelligence in the social classes have long argued their case with the proponents of the environmental cause ... But whatever effects innate intelligence may have on the social mobility of individuals, current theories in genetics cannot by themselves account satisfactorily for the observed class distribution of low intelligence.’