Heather's favorite number is two. She has two arms, two legs, and two pets. And she also has two mommies. When Heather goes to school for the first time, someone asks her about her daddy, but Heather doesn't have a daddy. Then something interesting happens. When Heather and her classmates all draw pictures of their families, not one drawing is the same. It doesn't matter who makes up a family, the teacher says, because "the most important thing about...