My non-scientific, non-medical mind tells me that genetics are the most important factor regarding pre-disposition to disease. What's interesting to me is how the evolving field of biotechnology might leverage gene therapy in the future to restructure a person's DNA to prevent or remedy medical problems. It seems like the technology is advancing at a rapid rate. But I know this also raises all kinds of ethical concerns. Nevertheless, I think this will be possible and implemented at some future time.