In the United States, your right to read what you want is protected by the First Amendment. In a free society, the author and reader are protected.
Source: USF Libraries: "The First Amendment"
Consider, too, the array of additional news items and podcasts available on the topic
If you want to try to find out why a book was challenged, search newspapers for the title of your book and "banned" or "challenged" to find specific cases. Example: "gossip girl" and (banned or challenged)
To narrow your results, add words like "school" (since that's where many challenges are made) or "parents."
Source: University of Illinois Urbana-Champaign Library: "Online Newspapers"