Interesting.
I wouldn’t say that our diet was much different than most folks, though when our son was younger we didn’t do a lot of fast foods, and we never bought soda, but we did have ice cream and cookies in the house.
But since he’s been able to drive (when he was 16) his diet stinks (LOL, spoken like a true “controlling” parent.) He’s been in college and now grad school, and rarely eats at home, but catches a bite on the run, which often includes to our horror, Krispy Kreme donuts, Red Bull, lots of Taco Bell and Chick-Fil-A. Still no cavities.
I did think of one thing that could account for some lack of cavities as a child. We had pit and fissure sealants placed on all his molars and kept that up until he came out of braces, so that might have some effect on keeping decay from taking root in his molars.
Caries is an infectious disease. If the caretakers of the child have untreated and open decay in their mouth the child is far, far, more likely to have a decay too.
If a child has rampant caries it is important to clean up **everyone** in the family and get them all decay free.
Also, chewing gum with xylitol helps a **lot**.