Few authors have won my heart as quickly as Nancy Kress. Two years ago, I had never heard of her. Suddenly I have seven of her books on my shelf, only one of which I've read. Like Octavia E. Butler does in Lilith's Brood, Nancy Kress uses genetic engineering to comment on what we consider human. With Nothing Human, Kress looks at humanity through posthuman eyes, asking where we draw the line…