There only two causes of dental disease.  Plaque (bacteria) and force (mechanics).  Plaque is what we all hear so much about when we are told to brush and floss daily.  The plaque is living bacteria that is part of the inflammation process occuring which causes decay and gum disease (periodontitis or gingivitis).  The mechanical aspect is the force we create when we bite together.  Genetics is not a "cause" of disease but it will allow the other two to be more harmful if our genetic makeup, dentally speaking, is not too good.  We can control two of the three, plaque and the force.  By taking control of these two, our genetics plays less of a role.  It is when the plaque and force are not controlled that a bad genetic makeup really adds up, ie., 1 + 1 = 5!  Because we cannot tell from one person to another what kind of a genetic makeup they have, it behooves us to control the two causes so we are not at our genetic makeup's mercy.