(Note: This edition of ST first aired back in April.) A century ago, women could not own property or vote. Today, women are the primary wage earners in about 40% of American households, and are poised to be a majority within twenty years if current trends continue. Washington Post staff writer Liza Mundy calls it "The Big Flip" and examines this huge cultural shift and its impact on gender roles, relationships, and social dynamics. Her book, "The Richer Sex: How the New Majority of Female Breadwinners is Transforming Sex, Love, and Family" (published by Simon & Schuster), looks at how some couples are embracing this reversal of traditional gender roles, how some rebel, and how others are simply trying to come to terms with this increasingly common reality in American relationships and households.