Winn was born and raised in Paris, the daughter of Irish and American parents.

[2] After graduating, Winn set a goal of writing "a novel a year until I wrote one that was good."

Before writing In Memoriam, Winn wrote three unpublished novels, worked on screenplays, and taught homeschooled children.

[7] In 2019, Winn started writing In Memoriam after reading student newspapers published 1913–1919 from her alma mater, Marlborough College.

[7] The protagonists, Gaunt and Ellwood, were inspired by her readings of and about Robert Graves and Siegfried Sassoon, respectively.