In Sharon Horgan’s new HBO comedy, “Youth,” Alex, a fiftysomething divorcée, struggles to adjust to her newly empty nest, only to find her son back at home after his first week at college, with nary an explanation. Horgan, the Irish-raised, London-based TV auteur, who tends to write and star in her shows, broke through stateside in 2015 with “Catastrophe,” and later went on to create “Divorce” and “Bad Sisters.” For Horgan, “Youth,” with its half-hour comedic format, is a return to form that tackles a new subject matter: a distant mother-son relationship and the complexities of both teen-age boyhood and being in the “sandwich” generation of life. In an interview with Inkoo Kang, Horgan discusses how she got the show green-lit despite never officially pitching it, about growing older with her series, and how her approach to autofiction has shifted throughout her career. Read their full conversation: