The 22-year-old rage-pop phenom and his father John Herndon, of the post-rock band Tortoise, chatted with Popcast about songwriting, nepotism and what they’ve taught each other. Subscribe today at nytimes.com/podcasts or on Apple Podcasts andSpotify. You can also subscribe via your favorite podcast app herehttps://www.nytimes.com/activate-access/audio?source=podcatcher. Formore podcasts and narrated articles, download The New York Times app atnytimes.com/app.Hosted by Simplecast, an AdsWizz company. See https://pcm.adswizz.comfor information about our collection and use of personal data foradvertising.