On my way out the door, my son says,"Dad, I have to poop."After all the work of bundling him up,"Go ahead," I say.He sheds his parka, drops his snow pants,and mounts the high white seat of the toilet.I unbutton my coat, loosen my scarf,let it hang from my neck, and wait.Almost immediately he calls from the bathroom:"Papa, check my bottom."I lean over the small of his back as he bows,lost in the flurry of my overcoat and scarf.I wipe the crack of his ass. He hops offthe toilet and pulls up his...