A new study of monozygotic twins raised apart in South Korea and the United States, has been published in the scientific journal Personality and Individual Differences. Monozygotic twins raised apart provides a unique test of the role played by genetics and the environment, as such twins have the same genetics, supposedly, assuming that epigenetics does not make a difference. In this study the twins were born in 1974 in Seoul, South Korea, but became separated, with one remaining in Seoul, the other being adopted and taken to America.