OP (assuming that your post is genuine):

Your family is trying to control your thoughts (literally!). That is bullying. All they have the right to do is to set ground rules for discussions with them. You have the right to do likewise.

In other words, your family has the perfect right to say, "I don't want to hear your opinions on the Newtown tragedy, ever." You, in turn, have the right to say, "Don't tell me how to spend my free time, ever. And don't question my sanity to my face, ever."