It may surprise you but as recently as the 1960’s we did not know what a gene was. It took the work of several scientists to first identify the gene and then decode it. Once done, it took over the world. It soon became common place to find a genetic underpinning for all sorts of ailments. You would also be negligent if you did not undergo a genetic test to predict the possibility of disease. If someone in your family was diagnosed with a disease, you would immediately test the rest of your family members lest they find traces of the same disease.
Do consider that if your genes alone could predict all disease all twins would witness similar medical ailments give or take a couple of years. We know for a fact that this does not happen. No two individuals, even twins, are identical, genetically speaking. A study at the University of Western Ontario showed that for example if one of two monozygotic twins had schizophrenia the other was only fifty percent at risk for the same disease. Clearly, genes were expressing themselves differently.
This led to the coining of the term exposome. Exposome is the combination of the specific external environment (your city, locality etc.) the general external environment (your country, economic development, facilities etc.) and your internal environment or lifestyle. Combined these result in or do not result in causing gene expression or the triggering of disease linked to genetic disorders. In a sense, this is good news as this means that even if you are pre-disposed, you still have a fighting chance to change the outcome. Epigenetics (means on top of genetics) is another emerging science that attempts to change the way genes are switched on or off without changing the underlying genes themselves. Exposome and Epigenetics collectively are worth a look if you perceive risk from a genetic disorder.