Bryan Sykes is a professor of human genetics at Oxford University and also operates a company that traces human genetic backgrounds. Think of him as a CSI detective for history buffs. Sykes tackles the Irish genetic code in his new book "Saxons, Vikings, and Celts: The Genetic Roots of Britain and Ireland." He traces the genetic makeup of many royal families, even those distant descendants who live all around the world in the 21st century. Sykes (author of "The Seven Daughters of Eve") conducted a ten-year DNA survey that involved 10,000 volunteers, seeking the genetic makeup of British Islanders and their offspring. Sykes also provides historical context and color, visiting Welsh caves and vividly describing burial rituals from thousands of years ago. A highlight for American readers is the chapter devoted to the genetics (and royal bloodlines) of the Irish in the U.S. ($26.95 / 320 Pages / W.W. Norton)