Human Nature: With an extraordinary new technology called CRISPR, we can now edit DNA—including human DNA. But how far should we go? Gene-editing promises to eliminate certain genetic disorders like sickle cell disease. But the applications quickly raise ethical questions. Is it wrong to engineer soldiers to feel no pain, or to resurrect an extinct species? Gene-Editing Reality Check: Scientists are beginning to use CRISPR gene-editing technology to treat diseases and alter the human genome. But as research advances, the ethical dilemmas multiply. Which illnesses—and traits—should be eliminated from the human experience?