Why is my sister eating lots of sweets and not getting cavities?

Its not just sweets: There are many reasons why someone may get cavities and some not. There teeth may be stronger, they may remove plaque better, and its not how much as it s how often you eat, drink or suck on any carbohydrate. So, watch your frequency of carbs, brush and floss better and use Fluoride to toughen teeth and chew sugarless gum after meals.

Cavities: There are different factors that affect cavities. One factor is how deep the grooves are in your teeth. This will vary from person to person. However, the biggest factor is the type of bacteria in your mouth. Your sister may not have high levels of the cavity causing bacteria in her mouth and you might. This can be tested in a dental office.