Genetics and psychiatry: an unheralded window on the environment. Two recent reviews in the American Journal of Psychiatry and the British Journal of Psychiatry reported on progress in understanding the genetics of psychiatric disorder. Both reviews focused on this progress as a prelude to psychiatric diagnostics and therapeutics based on molecular biology. Neither review recognized that the latest data in behavioral genetics support environmental causes for abnormal development and psychopathology as much as they support genetic causes. Moreover, these genetic data point clearly to a type of environmental cause with central importance: the environment that is specific or unique to each sibling in a family. 