This study investigates the relation between early life conditions and adult obesity in France, using a rich data set collected through the 2003 nationally representative Life History Survey. No salient factor emerged in men, while in women, after controlling for current socio-demographic characteristics, a relation was found between obesity and the following factors: father's occupation (OR=3.2 for women whose father was a clerical worker, versus those whose father was in a higher-level occupation); experience of economic hardship in childhood (OR=2.0), and; high parity (OR=2.1 for parities of more than 3 versus parity of 1). Neither early family history nor mother's working status surfaced as significant factors. Those findings highlight a definite gender pattern, with a strong association between early disadvantage and obesity in women, but not in men. Potential mechanisms are discussed, particularly the "habitus", the "thrifty phenotype" and the "feast-famine" hypotheses, and possible interactions with childbearing and motherhood. An integration of social and biological perspectives is needed to reach a better understanding of the processes involved, and to achieve progress in primary and secondary prevention.