My sister and I never had any cavities as kids. However once my sister hit around 18 she got a couple. I just went to the dentist and got word that I have three all of a sudden. As a kid I maybe brushed once a day, nothing else. Now I brush twice a day, use floride rinse and floss. So why did I get hit with three cavities? Is there a connection between age and cavities, something genetic possibly?