Scientists for the most part have identified what causes cavities but studies show that there are some genetic risk factors that could make people more at risk for cavities.

1. Genetic sweet tooth- Scientists have found a gene variant that’s associated with sweetness preference. If someone is genetically wired to prefer sweet things they are more likely to eat the foods that contribute to cavities.
2. Soft enamel- Some people have a genetic predisposition to softer tooth enamel, making it easier for the enamel to get eroded and cavities to form.
3. Taste ability- Genes contribute to the ability to taste a wider verity of flavors. People with a stronger taste ability are less likely to be drawn to foods that are bad for your teeth since they appreciate more flavors in more foods.
4. Saliva quality- Saliva is important in remineralizing your tooth enamel, rinsing food debris away from your teeth, and breaking down food for digestion. Having bad saliva genes can negatively impact your dental health.
5. Immune response- Your mouth is home to a wide range of bacteria communities. If your mouth is full of communities of healthy bacteria there is less space for unhealthy communities. If your genetics make your immune system attack the colonies of healthy bacteria, however, you mouth could contain more of the unhealthy bacteria.

http://www.cnn.com/2014/07/03/health/tooth-decay-causes/