My next younger brother (63) is like you: indestructable teeth. Even though he has not taken very good care of them. Maybe two cavities. Drinks soda pop like water. And his baby teeth didn’t start falling out until he was a couple years older than I was when mine fell out.
The human body is unfathomably complicated. One size never fits all. My gramps was a dentist and he had all sorts of problems culminating in radiation poisoning from the army.
When I became an RN I learned quickly one can get a history of family but that one person...that one set of chromosomes or problem is an anomaly and doesn’t fit, and yet it’s right there in front of you.
You’re right, some people can care for their teeth, floss, regular check ups, carry a brush everywhere and they’ll rot no matter. Another brushes once a day and no cavities, no gum issues for decades. It’s kind of not fair but what can you do about it?
Take care.