Behavioral genetics is the identification of behavioral traits that are genetically determined, the identification of the genes that are involved, and the discovery of modes of intervention to alter the expected course of the disease. Unlike the classical Mendelian traits, many specific aspects of behavior are, in part, determined by several genes. The corresponding abnormalities of behavior or deficiencies are therefore polygenic. New genetic techniques are leading to the discovery of these genes, and the techniques and knowledge developed in the Human Genome Project make it possible to screen the genome of any individual for the presence of known polymorphisms. This raises great hopes for diagnosis and the individualization of therapy. However, the genetic prediction of unacceptable behavior can further lead to social and occupational discrimination and enforced therapy. This raises serious concerns about how this information will be collected and who will have access to it.