Are our personalities inherited or made? What can DNA reveal about human history? How significant was the creation of Dolly the sheep? And will we soon be designing babies to order? Mark Henderson, science editor of 'The times', distills the central concepts of this newest of sciences in a series of 50 lucid and engaging short essays. Beginning with Darwin's theory of evolution and concluding with the most recent, and controversial, scientific advances, he shows how knowledge of our genetic code has changed our understanding of life on Earth