Human Nature: Our DNA can determine attributes from eye color to medical predispositions. 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? And is there harm in allowing parents to choose their child's features, like eye color or height? The scientists who pioneered human genome studies and CRISPR grapple with these questions. CRISPR Gene-Editing Reality Check: The revolutionary gene-editing tool known as CRISPR can alter, add, and remove genes from the human genome. The implications are immense: It could help eliminate illnesses like sickle cell disease and muscular dystrophy and could even allow us to alter the genes of future generations of humans, leading to so-called designer babies. But will this ever really happen? Medical journalist and pediatrician Alok Patel investigates the current state of CRISPR—starting with a bull calf named Cosmo. Patel discovers how scientists edited Cosmo's genome so he would produce more male offspring and what that means for humans. In conversation with scientists, artists, and ethicists, Patel explores what kind of gene editing is actually possible right now—and what we should be thinking about when we consider manipulating human traits and, ultimately, the human experience.