Racism vs. Homosexuality in the HS Classroom

I was interested, when we were talking about race, racism, and To Kill a Mockingbird in class on Monday, because I am curious as to what "taboo" subjects are not ok or not ok to teach in public school classrooms. As most of us have confirmed, we had read To Kill a Mockingbird at some point in school. Many of us recounted how the issues of race and racially discriminatory language was addressed in a classroom. Yet, I feel as we talked about The Price of Salt or Giovanni's Room none of us had read these texts, or what I realized were probably any homosexual texts in our high school classrooms. So the question I asked myself was why...is it because there are not necessarily well-known homosexual texts to be read in a classroom setting, or is it because of the subject matter?

Do people feel that it is ok to talk about racism in a 1960's text written in the time period of the 1930's because it is so long ago? Do they feel this type of racism no longer exists, so it is ok to discuss it, and discuss it as a past-tense situation? If this is the case is this why a text such as To Kill a Mockingbird is taught, yet a text dealing with the issue of a gay relationship is not? Is the issue of homosexuality too "present" for our society that to teach a novel dealing with homosexuality to a high school class would cause and raise too many questions? If Dominique is telling us in class how uncomfortable she was having to sit in a classroom with peers who clearly misinterpreted the reason they were reading To Kill a Mockingbird are schools worried that the same such incidents would occur if a text with homosexuality was read?

I just want to understand why it seems that it is ok to address racism in a text in a high school classroom more than homosexuality.