The number of Californians 50 to 64 who live in their parents' homes has surged in recent years, reflecting the grim economic aftermath of the Great Recession. Debbie Rohr lives with her husband and twin teenage sons in a well-tended three-bedroom home in Salinas. The ranch-style house has a spacious kitchen that looks out on a yard filled with rosebushes. It's a modest but comfortable house, the type that Rohr, 52, pictured for herself at this stage of life. She just never imagined that it would be her childhood home, a return to a bedroom where she once hung posters...