Nepo babies are all the rage, but few families have a business as niche as the McFerrins. Jazz vocalist Bobby is best known as the singer of Don’t Worry, Be Happy, the first a cappella song to top the US charts. More than three decades later, his daughter Madison picked up the baton, releasing two vocal-only EPs that looped and layered her voice into a faintly retro melange of soul and R&B.