A few years back, not long after Dolly the cloned ewe was sprung on an unsuspecting world, an Australian researcher reported that DNA was so ubiquitous it was literally oozing out of our pores. It's 50 years since Cambridge-based scientists James Watson and Francis Crick started the genetic revolution with their depiction of what deoxyribonucleic acid, or DNA, looked like (a double helix, like an entwined pair of circular staircases) and how it might replicate itself. Scientists began talking about ridding the world of inherited disorders like Down's syndrome, of tailoring drug treatments to an individual's genetic makeup, of stopping cancer in its tracks, of finding the DNA switch to extend the human lifespan, of ending global hunger with disease-resistant foods, of growing new pharmaceuticals simply and cheaply in a field of wheat. Still, thanks to gene therapy, at least a dozen young boys in France, Britain, Italy and the U.S. are living near-normal lives, released from the virus- and bacteria-free "bubbles" where they'd been confined after being born without an effective immune system. The genetic revolution has fundamentally changed the way we think about disease.