Ofcourse your story covers an extreme situation, which makes judging peoples actions difficult, but I can't hold it amymore. How fucked up are Andy's and Matts' parents? They react pretty well to the stuff they get to know in the chapter, but overall they seem to have the wrong image of teenagers. They want to know why their sons did never tell them they had sex, well I can answer that question. BECAUSE IT'S EMBARASSING. I like the thought's on psychology in these books. But I don't understand why none of the characters just comed out and tells those hypercurious that sex is nothing you wanna talk about with your parents. If they want honest answers, they should ask more subtle questions. If they are suspisious , they should just convince their children not to have sex in a general discussion, instead of trying to make them admit their sexual activities. (Just my POV as I am a teenager myself.)
Still a great story though, it surely has a lot of tension to it!