Really? Seems like that one would hasten the guns coming out.
So. D’you think the rain will hurt the rhubarb?
This is a silly thing to talk about. Instead, let’s talk about how cute my new baby is and how all the other parents wish they had a baby as cute as mine.
Obviously you’ve been at the same family gatherings with my brother and my brother-in-law.
My sister and I just leave the room and talk about if the sweet corn is going to be as sublime eating this year. There is room for you on the couch as long as you are appropriately serious about sweet corn. Discussing homemade cinnamon rolls works also as long as you understand what is the right kind and amount of frosting.
Join us.
“That’s interesting. Well, we better start drinking these beers before they expire”
works every time.
Is this necessarily a bad thing?
“Yeah, let’s not go there” could be as effective as anything else. Chances are your family knows your buttons. Might as well just call them out when they start pushing.
Yes, changing the subject needs to be a subtle maneuver here. We’re dealing with strong, different characters.
We do want to live in harmony, but there is a constant negotiation as to what our common attitude toward the external world should be and the elements that this attitude consists of are… let’s say many.
Maybe then something like “Yeah, I know what you mean.” Doesn’t mean you agree, doesn’t mean you disagree, and adds nothing to the conversation. Then maybe the topic dies on its own and you can organically move on to other things.
“I know what you mean” means different things in different contexts. A conversation is a continuous flow, with occasional pauses, indeed, but not a structure with isolated segments. It’s not that easy. Once a subject is brought up I usually know where the conversation will lead and what I will have to agree with eventually. If I am agile enough, I may steer the discussion in a different direction, but teenagers are tricky.
Ah yes, teenagers. I have a teenaged nephew who has some rather strong opinions. Rather than change the subject, I engage him; make him define his terms and justify his positions. We’ve had some very interesting and respectful conversations, and I like to think I’ve helped him think more critically.
Sorry, though, that’s specifically not the advice you asked for.
But I’m just a random contributor to this thread. I have not initiated it.
I sometimes ask for advice. But not usually. Hmm. 
Oh, shoot, I got mixed up and thought you were the OP. Sorry, @purplehorseshoe. I hope at least some of this discussion has been helpful.