Cloninger’s typology has been commonly cited to classify alcoholism into type I or type II. This was developed by Claude Robert Cloninger, an American psychiatrist and geneticist. Type I is for males and females who have both genetic and environmental predispositions, have started manifesting alcoholism in the later stages of development, and can be classified as mild or severe. Type II is for sons of male alcoholics who only have a mild environmental predisposition, had started manifesting alcoholism earlier (adolescence or early adulthood), often have a moderate severity, and have engaged in criminal activities. This typology was based on the results of a longitudinal study on 862 Swedish adoptees and their biological as well as adoptive parents.