How Much Should Reading Be a Mirror, and How Much a Lens?

I saw a post recently about parents getting upset about a book the teacher was using in class.  I can't remember what book it was, but the bottom line was, as I've found to be pretty normal in such cases, whose worldview was to be presented to the kids--that of the author or that of the parents?  

There are those who say that kids who are being brought up in homes where LGBTQ people are seen as sinners and/or freaks need to see books that present them as normal people with normal goals and feelings---books that normalize what these kids are feeling--and yet those kids' parents don't want that behavior normalized.  

There are parents who vehemently object to having their children read Mark Twain's books with the character Nigger Jim (sorry, I refuse to say N---, I won't call anyone that or use it to describe anyone today, but if I'm going to refer to the word, I'm going to use it) because they consider the word "Nigger" to be SO offensive, while other people believe Twain to be a big enough part of American literature that reading his works is a must.  One group is afraid of the  normalization of the use of an offensive word--or at least the failure to absolutely condemn the use of the word, and another points out that the protagonist respects Jim--something that wasn't necessarily normal at the time the book was written.  

But what about when you get away from reading assigned to kids or books available to them?  What about when you are talking about adults who are responsible for their own reading choices and their own moral and cultural choices?  As adults should we strive to be "inclusive" in our reading material?  Should we seek out fiction that challenges our worldview, or criticize a book because it promotes a worldview different from ours?  

I am a conservative Catholic.  My views on sexual morality are probably more conservative than 90% of the country--I know it and I own it.   However, my taste in reading material is far more liberal than my beliefs--I don't automatically turn down books because they have sex scenes including sex scenes (no matter how graphic) between unmarried people, despite the fact that I believe non-marital sex is wrong.  On the other hand I have absolutely no desire to read a gay romance.  

I've read a lot of Christian fiction over the years and often got annoyed if I thought the author mis-represented Catholicism.  However, I  don't have problem reading about how Protestants live Christianity, or about the Amish (though I don't like it when the point of the book seems to be to show how awful the rules of the Amish faith are).  I've enjoyed books about Muslims being Muslims.  I don't have to agree with the author's beliefs, or the beliefs of the characters I read about, but I don't like it when I'm told that my beliefs are wrong--particularly when authors mis-represent my beliefs. I know there are people who absolutely refuse to read anything classified as Christian fiction even if reviewers say it isn't preachy because so much of it promotes a world view with which they disagree.  Most people I know decide if a book by a political figure is worth reading simply by looking at who wrote it--and if the person is on the wrong side, they pass.  

Some of the many challenges floating around on book blogs deal with diversity or multi-culturalism.  Bloggers say they will read a certain number of books about other cultures. I will admit I rarely seek out such books, but I'm not averse to reading them.  On the other hand, I do like finding books about people like me--married women with grown kids, women facing life post-children, women who are closer to my age than to my daughter's.  I like books set in my part of the country and books with a Catholic bent.  

To what extent should our reading be a mirror--sending our beliefs (for good and bad) back to us, showing us what we look like, and to what extent should it be a lens through which we can view the other side of the story?