The main character of Brad Watson’s fourth book was inspired, first, by a childhood memory. “I saw her,’’ Watson said, “when I was, I’m guessing 6 or 7, at my grandma’s in the country. We used to go there Sunday afternoons. And one day they brought this little old lady in black, and someone said, ‘That’s Aunt Jane; something’s wrong with her.’ ’’

Although Watson never learned his great aunt’s exact diagnosis, he learned some details over the years — she was incontinent; she never married; but she had been popular with the boys and loved to dance. “I saw a picture of her when I was in my 20s, in a shoebox of old photos,’’ Watson said. Aunt Jane was wearing a summer dress and hat. “I thought it looked like she was flirting with the camera person,’’ he added.

And with that “what little we knew, and imagination, just kind of fluttered together,’’ Watson said. The result is “Miss Jane,’’ a novel set, like much of Watson’s work, in his native Mississippi. At the book’s center is Jane Chisholm, born with persistent cloaca, a real, though rare, medical condition that Watson suspects would explain what set his aunt apart from the life of marriage and motherhood expected of women in her era.

Creating an authentic voice for Miss Jane was a challenge made easier by Watson’s memories of the “strong, interesting women’’ he grew up around and whose conversations strongly influenced him. “The men were pretty good storytellers, too,’’ Watson said, “but the stories the women told — they were layered, and they had depth. I just felt like I was able to absorb a lot from them, and it made me very respectful of women, especially older women.’’

Watson will read 7 p.m. Wednesday at Brookline Booksmith.

Kate Tuttle, a writer and editor, can be reached at kate.tuttle@gmail.com