In 2012, biochemist Jennifer Doudna and her team at Berkeley figured out how to rewrite our genetic code using a system called CRISPR. Thanks to this miraculous discovery, we now have the power to hunt down cancer cells, deflect oncoming viruses, and cure genetic diseases. But CRISPR has a dark side, morally speaking. We'll soon have the power to give our kids superior strength and intelligence. Should we do it?