As scientists learn more about how genes affect everything from hair color to sexual orientation and mental health, we’re faced with moral and political questions about how we allow science to intervene in the genetic code. In this episode, Siddhartha Mukherjee, the author of the new book “The Gene: An Intimate History,” talks with David Remnick about the intimate and global implications of modern genetic science, and speaks frankly about his own family history of mental illness. Plus, we visit the studio of a leading sound-effects artist, and a virtual-reality team struggles to make a V.R. experience that lives up to the hype.