The article explores how separated parents can share the costs of raising their children, treating children as a public good. The mother controls the child's spending, while the father can only give money. The study finds that when the parents' income is high, they spend more on themselves than on the child. If the parents can reach an ideal sharing arrangement, they will eventually settle into it. If not, their spending patterns will keep changing. When the law enforces child support payments, the mother's spending compared to the child's increases.