Yeah, I have similar genetics. And immediately I imagine someone reading this and saying "lol those assholes blaming genetics for not taking care of their teeth", but what I'm referring to is my parents' dental history--worse than mine by a lot, like, one third, maybe--as well as the online commentary evidence that a non-trivial minority of people have seriously good genetics (brush lazily, only occasionally get checkups, still no cavities by 20), and people who say they've been very consistent with yearly checkups and following advice and still have the same yearly increase of cavities. Not to mention articles about dental biotic variations, people with an oral biosphere which is relatively hostile to the particular bacteria which feed on sugar and excrete strong acid, vs. people with a different biosphere which is much less tolerant of those bacteria.

This is something funny I didn't mention in my previous comment because it seems confusing to the whole issue, but the same friend I had who got the "your teeth will all fall out and you'll die" diagnosis, who immediately left and never returned to that clinic--I first heard about this because I asked if she had any recommendations for dentists in the city, and she actually recommended this one, with the strong caveat that they told her all her teeth would fall out. When I asked and pressed her on this point, she didn't have a good explanation, more like an embarrassed "yeah the dentist I saw was horrible, but I think the clinic is probably good overall, but yeah I'd never go back". I still don't know what that was about--I should be seeing her in a few days and will try to pin down an explanation.

The best thing I've heard from anyone as a "always do this" point with dentists is to request a copy of the xrays (in email I guess). And maybe even an explanation of them! (The better to take both the xrays and dentist explanation, to get a second opinion and double check.)