Abstract

The present study discussed the history, methodologies, findings, and the problems in behavioral genetics. The results of twin and adoption studies and those of molecular genetic studies that identified genes influencing human behaviors have been briefly reviewed. Twin and adoption studies indicate that most human behavioral traits are heritable, although the magnitude of heritability varies. Twin and adoption studies suggest that environments ate also important in determining human behaviors. The relevant environmental factors, however, appear to be largely those that are not shared by family members (e.g., accidents or birth order) rather than those shared by family members (e.g., family socio economic status or parental rearing style). In general, genetic influences on most behavioral traits tend to increase with age, whereas shared environmental influences decrease. To date, most human behavioral genetic studies have been conducted for middle class Caucasians residing in the Unites States, Australia, and Northern European countries. Because gene frequency and cultures differ among ethnic groups and races, it is difficult to apply the results of behavioral genetic studies performed in Western societies to Koreans. It is necessary to conduct twin, adoption, and molecular genetic studies in Korea to resolve the issues of how genes interact with Korean cultures and relate to behavioral development in Koreans.