Dean H. Hamer is chief of Gene Structure and Regulation in the Laboratory of Biochemistry at the National Cancer Institute. For the past nine years, Dr. Hamer has studied the role of genetic inheritance in human behaviors, personality traits, and cancer risk-related behaviors such as cigarette smoking. His book The Science of Desire, co-authored with journalist Peter Copeland, was a 1994 The New York Times "Notable Book of the Year," and their new book, Living With Our Genes, is a science bestseller.