For the past 15 years, synthetic biologists have been figuring out how to synthesize an organism’s complete set of DNA, including all of its genes. They’ve tackled the genomes of microbes, but now one large consortium has its sights set on the human genome. The cover story in Chemical & Engineering News (C&EN), the weekly newsmagazine of the American Chemical Society, explores Genome Project-write (GP-write) and the technical and ethical challenges it faces.