This article examines the interdependence of the fostering status of children, their school attendance and their labour supply in host families in Niger. We appreciate the ethnic cultural heritage of fostering, a phenomenon assumed to be rooted in the long run and transmitted along generations. The focus is on the effects of fostering on children's outcomes. We specify a simultaneous equations model with three outcomes for children (school attendance, hours of market work and hours of domestic work) and a treatment variable (fostering). The results show that foster children are more likely to attend school and to have longer hours of domestic work than biological children. Importantly, we find evidence of a schooling fostering for boys and a domestic fostering for girls. All in all, ethnic inherited values and behaviours are found to have an important role in perpetuating fostering institution and on children's welfare.