a branch of psychology and genetics that studies hereditary and genetic factors that affect the psychological characteristics, behavior and development of a person. Psychogenetics investigates how genes and their interactions with the environment determine cognitive ability, temperament, emotional regulation, predisposition to mental disorders, and individual differences in behavior. Psychogenetic techniques include twin and family studies, genetic mapping, molecular genetic analyses, and longitudinal developmental studies. The goal of psychogenetics is to identify the mechanisms of hereditary predisposition to psychological traits and disorders, as well as to understand the interaction of genetic and environmental factors in the formation of personality and mental health.