It basically comes down to diet and hygiene. Yes it is true that some people are more susceptible to decay than others, but what can be controlled is how well the teeth and gums are being cleaned on a daily basis and what the teeth are getting exposed to.
Diets rich in sugars and acids will increase the risk of decay. Furthermore, the frequency in which the teeth are exposed to these will further increase the risk. While children need snacks and “grazing” in general is shown to be a healthier method of eating for the body, it has been shown that the frequent exposure of teeth to sugars and acid is what puts them at most risk. Its not the breakfast, lunch and dinner that causes the increased risk for decay, its all of the snacks in between that do. One strategy is to try to brush and floss after each of the “big 3” meals and to consume sugar free foods that are not acidic for snacks.
If you have any other questions about cavities prevention, feel free to ask any of your dental professionals at DDS.