“It’s no accomplishment to have or raise kids,” Woody Allen often used to say. “Any fool can do it.” Then in the fall of 1979 he met Mia Farrow, who had seven children. Mia, he now says, “introduced me to a whole other world. Yet the two of us have so little in common that it always amazes us. We’re always marveling on why we threw in our lot together and stayed together as long as we have.”