Alcoholism, however, is a complex disease, with multiple genetic and environmental factors contributing to the disorder. As a result, it may be impossible to specify a particular inheritance pattern of the disease. In this instance, researchers can use another type of statistical test called nonparametric linkage analysis as a powerful tool to identify genes involved in the disorder. This statistical approach, which does not require a specific model of how a disease is inherited, typically involves identifying families with many affected family members who are thought to have inherited genes that increase the susceptibility to the disease.
