Amazon has had a rocky history with censorship and apparent censorship. There was the time that they took a great number of books regarding homosexuality out of their sales ranking system, flagging them "Adult content" without regard to their actual sexual content (included were "children's books, self-help books, non-fiction, and non-explicit fiction"). And there was the time that they caved to public pressure and stopped selling a book on pedophilia, while maintaining that despite their actions they did not condone censorship.
Now, Amazon.com appears to have pulled a number of self-published fictional erotica titles from its virtual shelves because they are incest-themed. Not only have they pulled them from sale, they have also deleted them from the Kindles of any user who purchased them. This has gone largely unnoticed, except, of course, by the authors and readers of the books.
The biggest problem with this, if it is true, is that Amazon just finished a lawsuit last year where it agreed, in legally binding terms, that deletions would only occur because of "failed credit card transactions, judicial orders, malware, or the permission of the user."