Twins generally attract us due to their striking resemblance. However, it is sometimes the surprise variances between identical twins that make them so remarkable. Recent research in Science Direct emphasized this, following the incredible reunion of identical twin sisters separated as toddlers and reared in radically different cultures.
Born in South Korea in 1974, these twin sisters spent the first two years of their lives together before being separated by accident at a bustling market. Despite the family’s urgent search, only one twin could be found. While one stayed with her Korean family, the other was adopted and reared by a couple in the United States, who had no idea she had a twin, let alone additional siblings.
The twin who grew up in America only learned her actual identity decades later, in 2018, after submitting her DNA to a South Korean organization that aims to reconnect lost family members. She subsequently heard about her identical twin sister and other siblings.
Following their reunion, experts excitedly investigated the sisters, intrigued by the central topic of many twin studies: how much are our personalities, mental health, and IQ influenced by our environment and upbringing?
Tests rapidly revealed something extraordinary: despite having identical DNA, the twins had wildly differing IQ scores. The twin reared in America scored 16 points lower than her sister raised in Korea—a far larger difference than the normal IQ discrepancy between identical twins, which seldom exceeds 7 points.
“The twins showed substantial differences in cognitive abilities that have been linked to strong genetic influence,” according to a study participant. Researchers believed that the twins’ frequent childhood concussions may have contributed to their lower IQ.
Despite their severe academic differences and quite different early circumstances, the twins had very comparable personality qualities. “Notable is that both twins are distinctively high on conscientiousness—indicating that both are purposeful, well-organized, dutiful, and achievement-striving,” the study’s author stated.
The research went on to say that the Korean-raised twin grew up in a supportive, loving atmosphere, whereas the American-raised twin had significant challenges with her adoptive family. Surprisingly, both sisters have shown comparable resilience, ranking similarly on measures of self-esteem and mental health.
Finally, this interesting study demonstrates how identical twins may be both stunningly similar and astoundingly dissimilar. Their narrative continues to pique scholars’ interest, shedding light on the never-ending intricacy of the nature-versus-nurture argument.