Human genetics is the study of the human genome and how genes are transmitted through generations. This book includes many of human phenotypic characteristics and a lot of human genetic disorders which have inherited behaviors (approximately 250 genetic disorders and 20 traits). It includes many of genetic traits and genetic disorders depend on a real knowledge which I have got from some volunteers I know well their pedigrees. It includes: Introduction, Basic concepts of human genetics, Explanation of genetics and related terms, Types of Treatable Genetic Diseases and Human Genetics Traits and Behavioral Disorders. Classification of genetic disorders: Single-gene, Chromosomal, Mitochondrial and Complex disorders. I have set a sequence of items that deal with all dimensions of that disease and chose that arrangement to facilitate the reader to understand the situation easily. Such as mentioning the synonymous names and definition of the disease, nomenclature, signs and symptoms, history of the disease, epidemiology, hereditary pathogens and its diagnosis, causes and genetic profile, chromosome or gene location, inherited pattern, risk factors, genetic counseling.