Commentary: the analysis of variance is an analysis of causes (of a very circumscribed kind).

question its utility. The practical relevance of claiming that some character in some environment is 80% heritable provides no guidance for how to respond—except in a purely ideological way, by arguing as first Jensen and later Herrnstein and Murray did that the measure indicates that there is a permanent genetically inferior underclass and that no amount of social engineering—to say nothing of social justice—will improve its lot. Biological systems are complex, non-linear, and nonadditive. Heritability estimates are attempts to impose a simplistic and reified dichotomy (nature/nurture) on nondichotomous processes. Real progress in genetics, developmental and behavioural biology will come from paying attention to Lewontin’s insistence that we attempt to analyse causes, not variances.