There is no question that each of us is genetically unique and that we all have genetic weaknesses and predispositions to certain malfunctions.
Genetic strengths do run in families as well as weaknesses.
That being said, whether or not we ever develop a disease to which we are predisposed is largely under our control. There is a large body of scientific evidence showing that diet and lifestyle play significant roles in the development of such diseases, and even in the reversal of such diseases should they occur. For example, schizophrenia appears to run in some families. What in fact may be the problem is an abnormally high genetic requirement for certain B vitamins and minerals such as zinc. Given adequate amounts of these nutrients, these people will never develop the disease.