  In studying eating disorders, for example, we find that social factors may explain particular epidemiological patterns, like different levels of eating disorder across populations. But social factors don’t tell us why only one girl in a family gets bulimia. To explain that we can look at a particular brain chemistry that puts her at risk (Steiger et al 2001). But that does not establish that neurobiology really is fundamental. Rather, nothing is fundamental. Culture or trauma may require biological mediation to have its pathological effect, and vice-versa. Neither one should be considered fundamental, but seen rather as the best way to answer a specific question about what makes a difference in a context.