Further things struck me as funny. The biographical points didn't sit well with my understanding of Nietzsche's chronology. So far as I'd extracted from countless sources, his deteriorating mind immediately left him on January 3rd, 1889. This was followed by a series of confounding, seemingly non-sensical letters (the eerie "Madness Letters") and absolutely no more writing; whereas the introduction to My Sister and I had it that while imprisoned in a mental asylum in Jena (a historically factual event) Nietzsche wrote a second autobiographical manuscript following Ecce Homo, which was smuggled out of the institution by a fellow patient to avoid the scrutiny (also historically factual) of Nietzsche's family. My previous understanding of the time between his March 1889 commitment and early 1890 release was that he was utterly incognizant and incapable of holding a pen.
Furthermore, the voice employed by Nietzsche in My Sister and I seemed fishy. While his 1888 writings employed an evolutionarily linear style characterized by increasing megalomania and hyperbole, My Sister and I seemed to be a polite return to his Beyond Good and Evil (1883) style, and more digestible and transparent than ever. I smelt a rat, and started vaguely remembering references to an apocrypha Nietzsche work.
Sure enough, I slogged home on my bike in the rain and went straight to the internet, and there it was - My Sister and I was a forgery almost immediately recognized as a hoax, denounced by Nietzsche translator gurus Walter Kaufmann and Oscar Levy (via his daughter, as Levy was dead four years before the first publication and discovery of the work) and omitted with near universality from the Nietzsche canon. First of all, there was no original German manuscript - the publisher of the original book claims it was lost. Kaufmann pointed out several examples, such as a mistranslation from the King James Version of the Bible and a reference to dogs and women as "bitches", where "Nietzsche"'s puns relied on the English language and simply couldn't have been conceived in German. The book was tied to Samuel Roth, a highly controversial publisher who did time in jail for unauthorized publishings of Joyce's Ulysses and who stood in highly dubious standing in the academic community. Kaufmann also claimed to have later received a ghostwriting confession from a little-known minor author named David George Plotkin - although as far as I can tell, no record of this admission exists beyond a footnote in Kaufmann's Nietzsche biography. Other, more recent critics pointed out that a list of "fascinating American cities" in the text was fronted by Detroit, a complete unknown city in pre-automotive 1890. They also note that the publishers of the original book claim nine editions (mine says thirteenth!), and this number surely cannot be correct and is being used as a tool of false legitimation.
So an open and shut case of literary forgery, right? Not so fast - fortunately for we lovers of a good mystery, there are some complications. It seems that around 1986 or so, scholarship slowly started opening itself up to the possibility that My Sister and I was legitimate. First of all, it seems that the book's quick dismissal could've come at the hands of its controversial content - not only did "Nietzsche" admit incest, but also an affair with Cosima Wagner (the wife of Richard of "Flight of the Valkyries" fame) and numerous other lurid sexual relations. Could Nietzsche's biographers be too stubborn to be open to this new damning information? There is also the claim that recently discovered letters of confirmed Nietzsche composition reveal information and display writing styles that, in the view of some, undeniably have the same author as My Sister and I. Spearheading this argument is Walter K. Stewart, whose book Nietzsche: My Sister and I - A Critical Study (my copy is in the mail!) stridently defends this stance in 188 pages. Also on board is Kathleen J. Wininger, who did her PhD work at Temple University - she has written an article on the subject which I am frustratingly unable to access. In addition to taking up the argument of the book's positive authorship, Stewart has a theory relating to the dogmatic process of canonization that he feels this case to be an example of - and I too am certainly critical of the arbitrary and subjective values employed in canonization. The 1990s reprint of My Sister and I by Amok Books is also apparently convinced of the book's legitimacy.
I suppose that my stance is pending a read of Stewart's book, but I must say that I am at this point quite convinced that My Sister and I is a certain forgery. My main consideration is the text itself. I find it very hard to believe that the explosion of Ecce Homo could be followed but such banalities (although the disarmingly benign Nietzsche Contra Wagner that would theoretically bridge the two autobiographies certainly presents a curious voice). RJ Hollingdale described My Sister and I as "pulp fiction" in a footnote, and I think this best describes the character of the book - it is front-ended with sexuality and seems to treat Nietzsche's biographical information and typical self-referencing spiel as a meaningless and arbitrary formality, bopping around from subject to subject without rhyme or reason and ignoring Nietzsche' sensational-yet-sensible flow of thought. The aphorisms are empty and redundant, and the philosophical thought is simply incapable of operating beyond base nominative ability. Ultimately, it is simply not as clever, literate or informed as the true Nietzsche.
However, I am hungry for a good counter-argument as I find the opaqueness of Nietzsche's biography endlessly fascinating. I eagerly await my copy of Stewart's book and will report back when it's been digested. Meanwhile, there aren't too many good spots for further reading to direct interested parties towards - here is Denis Dutton's review of the Amok Books reprint, and here is the Wikipedia article, much of which was written tonight by me, but which also has extensive print references.