Through my medical experience, I ran across many medical cases of genetic diseases and hereditary ailments. In here, I liked to share with the reader; in a simplified manner, excerpts of medical cases connected to specific families and lineage, delineating the causes, symptoms and the means for protection of those genetic diseases. Historically, one of the most known cases is hemophilia that was transferred from generation to the next in the Queen Victoria's family. Tracing diseases in the family tree is beneficial in revealing the potential of spreading such diseases among offsprings. Dr. Ayman Elhossiny is specialized in internal medicine. He has authored many books in Arabic and English published, by distinguished publishers in different countries. The books provide a layman look at difficult health and medical problems. In this book, Dr. Elhossiny addresses a distinctive medical topic that is of interest to a multitude of readers.