Everyone has a mixture of genes, "good" and "bad", and it's largely one's lifestyle that determines how those genes get expressed. Poor lifestyle habits will likely trigger disease whereas good lifestyle habits can keep genes for disease turned off.
Study Epigenetics and you will learn that we are largely in control of our genes, not the other way around. To believe that genes are in control when disease appears is to believe that you're a victim (victimology 101).