the ethical and societal repercussions of intentionally mutating embryos to create "better" humans. Writing with fellow researcher Samuel Sternberg, Doudna shares the thrilling story of her discovery, and passionately argues that enormous responsibility comes with the ability to rewrite the code of life.

gain entry). Still, delivery is "a critical challenge in this field, there's no question about that," she says. A patent battle between Editas and Doudna's group at UC Berkeley is also part of the mix. The U.S. Patent and Trademark Office awarded the first CRISPR-related patent in April 2014 to the B