« If you love me, follow me. » Sibling's migration in France, 1870-1940

Recent works emphasize the role of the family in migration decisions. They particularly insist on the specific schedule of mobility that depends not only on individual life-cycle but also on the situation of the whole family at a given time. French military registers provide us with very detailed information on migrations, scarcely available in other sources. . We consider the smallest family group, male siblings, and focus on their life-cycle migration behaviours. We start by testing the simplest family indicator, birth rank and we show that, by itself, it has no effect on migration decisions. Mobility is not constrained by the order of birth among brothers. We then study whether or not there is competition among siblings and, in particular, if the migration of one of them encourages or prevents mobility of the others. Comparing the chances for an individual to move before and after the migration of his brother, we show that brother mobility did have a positive influence on someone's own mobility. But this result holds only for short distance migration. In other words, the short distance migration decision of an individual is heavily influenced by his brother's own short distance migration. Therefore, we argue that this kind of mobility is a collective decision that depends on family strategies whereas long distance migration, which is much more costly, is constrained and heavily dependant on individual characteristics such as his occupation before mobility. This approachs heds new light on the migration process and insists on its family component.