OK, I give up! What textbook says bad things about gays and lesbians? They must of really changed since I was in school.
The most read text book and the perennial sales leader in the US, regardless of genre, The Bible, touches on that subject.
I can't say that the Bible says bad things about this form of deviancy but it certainly doesn't promote it. The key passage that rings in my ear: For the wages of sin is death