A giant step for medicine or the most serious threat to personal freedom yet? A cure for cancer or an invitation to genetic discrimination and the search for a master race? Here, not a minute too soon, is a behind-the-scenes account of the Human Genome Project, the most ethically and politically complex scientific undertaking of this generation. Dubbed the ''Holy Grail of Biology,'' the Genome Project will occupy over the next five to 15 years a majority...