If so, tell your story in the comment thread.
Keep in mind that a book ban entails more than a library or school choosing to remove your already published book from its premises.
Publishers, via omission, "ban" good and even excellent book manuscripts by rejecting them. Often, agents and editors will tell you that while your book is interesting and well-written, it has no market and will not sell enough to justify its cost.Fortunately, the marketplace is being shaken up with e-book publishing; getting published cheaply and getting one's book indexed online are now realities for those who go the self-publishing route. But keep in mind that search engines also have their ways of filtering information by burying it deep.
Book distributors typically ban self-published books from their distribution systems, almost ensuring that a book will not reach its market.
Book reviewers, who seem to fawn all over celebrities and their often lightweight tell-all books, tend to stick their noses up at self-published books, no matter their literary merit.
Bricks and mortar bookstores often refuse to stock self-published books, and when they do, the self-pubs will get shelved in out-of-way spaces.
This suggests that we have to get creative in getting our books indexed properly--one reason I have set up this site, which is doing surprisingly well, considering its newbie status (11 days old).
It has been suggested by establishment publishers that the "cream" will always rise to the top, but this is simply not true. The "cream" is decided by a few powerhouses in the publishing industry. Otherwise, how is it possible for poorly written celebrity books to hit the best seller list? How people connected to the publishing industry always seem to find publishers willing to take a chance on their books?
In the U.S., public schools and libraries face the wrong side of the legal system when they try to ban books from tax-payer public institutions, although some overly-sensitive souls will attempt to do so via backdoor techniques.
So it is unlikely that your book will be totally banned in a public venue. Most likely, it will be moved to an adult section, which is not always a negative thing. After all, you wouldn't want to find Last Tango in Paris shelved next to Charlotte's Web.
However, if a book is restricted in such a manner that accessibility is nearly impossible, then that's a problem.
Food for thought.