The influence of hereditary and environmental factors is indispensable as the foundation on which the temperament of an animal is formed. Genetic research on animal temperament has experienced a turning point in recent years as a result of the development of molecular biology. In the near future, it may be possible to explain the formation process of animal temperament as the two fields share their research. We look forward to applying these research results to the development of new genetic treatment methods for problem behavior and training programs suited to the individual.