In Germany children are obligated to help their parents in the household as long as they live with them. This extends to family business. By law the children have no right to be compensated, since they are already compensated by the parents feeding and housing them. Of course, this doesn't mean parents can just slave their children, there are plenty of health and security laws and what's generally reasonable for a child of varous ages to do.
So no family sweat shop. but the bottom line is: in Germany kids are obligated to help out the household they live with.