If a mother stays home, the risk of both parents dying and leaving children orphaned is reduced. Man is mortal. If something happens and both working parents die while outside the home, who will take responsibility for those orphaned children? That's why mothers should stay at home and look after their children. Men are harder workers, so they're the better choice to hold a job. Plus, by having the mother at home raising the children, have a higher chance of being more righteous and well-behaved.