Is health inequality in France due mainly to unequal opportunity caused by circumstances such as personal origin, or to differences in individual behaviour? This question is important for defining health policies. According to the philosophy of responsibility, health differences due to factors determined by individual responsibility-such as chosen risky behaviours-may be regarded as “legitimate” because they stem from individuals' deliberate life choices. Consequently, one should not attempt to level these differences through remedial policies. By contrast, one should try to alleviate or offset unequal opportunity determined by factors other than individual responsibility, such as personal origin. We seek to assess the share of perceived health inequality due to childhood conditions and the share due to risky behaviour. We consider two possible ethical positions regarding the correlation between personal origin and risky behaviour. The first views the direct effect of personal origin on health as the only source of unequal opportunity. The second approach regards the indirect effect of personal origin on health as an additional source of illegitimate inequality. The 2006 IRDES survey on Health and Social Protection contains an ad hoc module of questions on childhood living conditions. Applying both approaches to the survey data, we demonstrate the massive contribution of personal origin to health inequality, regardless of the choice of ethical position. Unequal opportunity accounts for up to 46% of health inequality, whereas inequality of risky behaviour does not explain more than 7%. The residual inequality is due to the influence of age and sex.