There is a black-and-white picture in my hallway, of me, Nancy, and Lizzie in the bath, when Nancy was eight months old and Lizzie two-and-a-half. I am gently biting Lizzie. Nancy, in turn, is gumming my face. All eyes are on the person taking the picture - Pete, who was, as the slight camera-wobble shows, laughing. There we are-a tangle of half-shared DNA, all interlocking with each other; all being watched over by the one who loves us best. If I had to explain to someone what happiness is, I would show them this picture.