Abnormal genes and abnormal gene expression do exist, and can be acquired or inherited. Bacteria and viruses can change genes or gene expression, and the abnormal genes or gene expression can then be inherited by offspring. Abnormal genes or gene expression may cause a chronic disease; or make a person susceptible to a chronic disease when a triggering event changes the genetic susceptibility into a chronic disease.
https://www.youtube.com/watch?v=WbG6mzYUnyU&feature=youtu.be&fbclid=IwAR07cSRiUzBpr1LyW6_XXDtifWuQI9z0N3RTdP37Hv9HXv6oyu1qvRAe1gg