I usually just try to say something funny and change the subject. But should I get considerably "colder" in my answers, as these people ask me the same things every time we meet,
No, you just keep saying the very same exact funny words.
Miss Manners suggests this tactic (not the funny, but the repeating exactly). I think the situation someone wrote about was being offered pot at a college party. The person didn't want to get into a debate or judgment about whether pot should be smoked, he just doesn't smoke it. Miss Manners says, "no matter what they say, how they try to twist the topic, just say 'I don't care to.'
Want a toke? "I don't care to." What, are you against pot? "I don't care to" You'll love how it makes you feel. "I don't care to" You think you're better than us? "I don't care to."
My boyfriend (now husband) had figured this out for himself.
He would say: "It is the policy of the United States Navy to neither confirm nor deny the existence of nuclear weapons aboard its vessels." (apparently it's what the navy says when someone asks, "does that sub in our harbor have nukes on it?" --appropriate for him as a military-history buff)
And he'd do what the Navy does. No matter how often they ask, no matter how they try to twist the question, they say the exact same phrasing.
I saw it work--an "aunt" asked him (in front of me!) when he was going to marry me. So he said, "It is the policy..." No, you kidder, really, are you going to get married? "It is the policy..." She turned to me: YOU tell me, then, are you guys going to get married? So, I said, "It is the policy..." You're impossible, she said, and she walked away.
It only took 3 times, ever, to completely shut up about it.
We used the same tactic about kids' names. When we were expecting our first, the family would ask if we had names picked out. I didn't want to have ANY conversations on this topic--I didn't want them suggesting names (what if someone annoying suggested a name I liked? and anyway, we *had* named picked out), and I was NOT going to tell people the name until the kid had a chance to use it (ew, ick, fingermarks all over your brand-new name).
So my quick-thinking husband said yes, when someone asked him did we have named picked out. What are they? of course was the next question. "Gomez if it's a boy, Morticia if it's a girl." No, goofy, really what are the names? "Gomez if..." So then they asked ME, and I said, "Gomez if it's..."
Again, nobody ever went further than 2 questions, and most of them just stopped asking.