This is the sort of thing that happens when novelists get together, Kingsolver says. In her case, she was staying with Patchett in the midst of a long book tour. When she asked how the new book was going, “Ann made this miserable face, and I said ‘O.K., let’s talk,’” Kingsolver said via email. They stayed up late into the night.

“As it happened, I have a friend whose mother had done the very thing that Ann’s fictional mother had done in her book, which seemed completely implausible to Ann,” Kingsolver said. “I talked about the circumstances as I understood them, and what had led to this unusual family trauma. How elements of it might be useful in a story. I remember it as a fun conversation — taking apart a fictional engine and pondering how it might go back together. For some of us, that’s the definition of a good time.”

Born in Los Angeles, Patchett and her sister moved to a farm outside of Nashville after their parents divorced and their mother remarried. (Their father, a police officer, was an inspiration for the father in “Commonwealth.”) Their stepfather had four children of his own, which made for complicated interfamilial relationships. Eventually, Patchett’s mother would divorce him, too.

Patchett has two stepchildren with her husband but has never had a burning desire to be a mother . Among other things, that gives her more free time in the day. “I never thought for a moment I could have it all,” she says. “Either I could have children, or I could write.”

But she has deep connections to an extended family that includes friends; book people; her mother and sister, who live nearby; and Karl, whom she began seeing after her brief first marriage collapsed. They dated for 11 years before making it official.

“If I’m getting married again, and I said I never would, then I’m all the way in,” she recalls telling him. “There’s no halfway. And if you ever leave me, look in your rearview mirror, because I’m coming for you.”