Following the Nietzsche scholar Walter Kaufmann, most consider the work to be a literary forgery,[1][2][3] although a small minority argue for the book's authenticity.

If legitimate, My Sister and I would be Nietzsche's second autobiographical and final overall work, chronologically following his Wahnbriefe (Madness Letters), written during his extended time of mental collapse.

The book was tied quickly to controversial publisher Samuel Roth, the putative owner of Seven Sirens, who had spent jail time for the unlawful distribution of a version of James Joyce's Ulysses (1922).

[1] Kaufmann claimed in a footnote in his Nietzsche: Philosopher, Psychologist, Antichrist (first published 1950) to have received a ghostwriting confession from minor author David George Plotkin in 1965.

Beginning in the mid-1980s, a handful of articles began to call for its reevaluation, including references to more recently-discovered journals and letters from Nietzsche and Cosima Wagner.