Autism Spectrum Disorders (ASD) are among the most common developmental disorders. Stereotypies, lack of flexibility, as well as abnormalities in social behavior and communication are characteristic features. In the 1940s, the initial search for causes led to misguided theories such as parenting mistakes and vaccine damage. Rapid developments in human genetics, however, are shedding new light on the causes of ASD today. The book provides an overview of the current state of knowledge and piques curiosity about the future. Questions regarding the nature, timing, and heritability of genetic changes, as well as the influence of environmental factors on genetic predisposition, are discussed. What role does parental age play? Can toxins or infections during pregnancy increase the likelihood of ASD? In the long term, specific genetic knowledge is a prerequisite for DNA diagnosis and potential interventions.