Monozygotic female twins raised apart: In contrast with previous research, the twins' general intelligence and non-verbal reasoning scores showed some marked differences

Personality traits, mental abilities and other individual differences: Monozygotic female twins raised apart in South Korea and the United States. Nancy L.Segal, Yoon-MiHur. Personality and Individual Differences, Volume 194, August 2022, 111643. https://doi.org/10.1016/j.paid.2022.111643

Abstract: Twins reared apart are rare, especially twins raised in different countries and cultures. This report documents the behavioral, physical, and medical similarities and differences of monozygotic female cotwins, raised separately by an adoptive family in the United States and the biological family in South Korea. Similarities were evident in personality, self-esteem, mental health, job satisfaction and medical life history, consistent with genetic influence found by the Minnesota Study of Twins Reared Apart and related studies. An overall twin correlation across thirty-eight measures was r = 0.95, p < .001. In contrast with previous research, the twins' general intelligence and non-verbal reasoning scores showed some marked differences. Adding these cases to the psychological literature enhances understanding of genetic, cultural, and environmental influences on human development.

Keywords: TwinsAdoptionPersonalityCultureIntelligenceValues