Discover why the new era of personalized, gene-based medicine is both ominous and promising — and relevant to everyone. What will it mean when most of us can afford to have the information in our DNA — all three billion chemical letters of it — read, stored and available for analysis? What are the moral dilemmas raised by the new technology? Will it help or hurt us to know our genetic destiny? What if such information falls into the hands of insurance companies, employers and prospective mates?