A healthy lifestyle enhances the immunity of human body against sickness. Yet, it cannot keep you from the threat of sickness that you were born with. Every year, countless of people with healthy lifestyle are killed by hereditary diseases, e.g. heart disease and cancers. Gene is the reason behind their sicknesses. If one of your family members is diagnosed with a disease that is caused by a deficient gene, there is a higher chance you carry that gene that can make you sick. However, for most of the time you do not realize the risk.