June is the country's most popular month for weddings, at least traditionally. But in recent years, marriage rates have dropped off. The current administration in Washington is trying to push a plan to encourage marriage, especially among the urban poor. The idea is to provide economic incentives to tie the knot, and thereby reduce the number of single moms. But perhaps this assumes a difference in values that isn't really there. So claims University of Pennsylvania Sociologist Kathryn Edin.