I recently spotted a white Kia Sedona bearing Laramie County plates driving south on Yellowstone Road in Cheyenne, Wyoming; maybe the driver had just been to one of their kids’ schools. Wherever it had been, the minivan was plastered with stickers celebrating “momhood.” A thought came to me: When did being a “mom” become a calling? Mothers and their allies have long been political forces. Think of MADD (Mothers Against Drunk Driving), founded in 1980, and Moms Demand Action, started...