As political origin stories go, Abigail Spanberger, a former House member from Virginia who is now the Democratic nominee for governor, has an enticing one. It hits the sweet spot of making her seem simultaneously exceptional and relatable. In 2014, Ms. Spanberger, then working for the C.I.A., was brainstorming with her husband and their oldest daughter about where her next posting should be. Kenya? Costa Rica? “And our daughter said, ‘Virginia!’” Ms. Spanberger recalled to a bar packed with...