Medical Genetics Viruses, ultraviolet (Uv) radiation, and chemicals can all damage genes in the human body. If particular genes are affected a person can develop cancer. Understanding how genes cause cancer though, first requires a basic understanding of several genetic terms and conceptsMedical Genetics Viruses, ultraviolet (UV) radiation, and chemicals can all damage genes in the human body. If particular genes are affected, a person can develop cancer. Understanding how genes cause cancer, though, first requires a basic understanding of several genetic terms and concepts