The year my oldest daughter turned 4, her little sister was born, and that spring, in desperation, I let her play more or less unsupervised in the neighbors’ yard. When I came up for air from the endless diaper changes and nursing sessions, I’d catch a glimpse of her through the family-room window. Sweaty, dirty, and wild-eyed, she ran behind the neighbors’ pack of crazy, good-natured, and mostly unsupervised boys.