Frankenstein and the gory gang: how the novel blazed a trail for high art horror
theguardian.com
theguardian.com
There's a book called The Man Who Wrote Frankenstein[1] that argues that it was actually her husband, Percy Bysshe Shelley, who wrote it.
[1] - https://www.amazon.com/Man-Who-Wrote-Frankenstein/dp/0943742...
I highly recommend Romantic Outlaws[1] a book which interleaves the lives of Mary Shelly and her mother Mary Wollstonecraft (mentioned in the article as well.) After learning more about her life, I felt authoring Frankenstein was pretty in character for Mary Shelley.
[1] https://www.amazon.com/Romantic-Outlaws-Extraordinary-Wollst...
In the same vein, would anyone contest Shakespeare's claim to the plays that bear his name if it were not for the fact that he was born a bit too low in the British class system?
Shakespeare authorship is a bit of a special case as there is a peculiar lack of evidence, as opposed to a mass of evidence that has to be explained away with a "conspiracy", or an expected lack of evidence, as in the case of Bach: most of his works were neither published during his life nor found in a manuscript with his handwriting.
It is interesting to note about Tiptree is that, after the revelation, is to look at the timeline of reviewer and commentator documentation from the time and how there was this whole chunk of the community that overnight did a 180 from thinking a male Tiptree was a decent to good writer to 'we / I always knew she wasn't that much'. Similar statements can be made for C.L. Moore, and others. (However, I don't mean to claim that the entirety, or even a substantial part of the SF community feels such, but I do find it interesting that the percentage of the community which does hold such seems to align, roughly, with the percentage of the relevant populations involved with the question of the authenticity of authorship of people such as Shakespeare and Shelley.)
edit:
The thing I think I'm trying to get at is that there seems to have been a shift, that is, Shakespeare and Shelley are so fundamental to a certain class of western identity, that it almost seems as the transfer of their authorship is to 'polish them up', because, while a few---if you were to just interview people off the street at random---know Austen and the Brontes, fewer Eliot, but who in the English-speaking world doesn't know some version of Frankenstein or that Shakespeare is supposed to be some big deal? (And even with Twilight, and what people seem to know of Heathcliff and Cathy, it's modernly, as with Jane Eyre, cast in the modern romantic (eros) mode, thereby deracinating them of their inherent social commentary.)