At the age of two, one of the twins became lost in a market in South Korea, leaving the sisters to live
The adopted girl did not know that he hadsiblings until she submitted her DNA to South Korea's family reunification program in 2018. Two years later, she received the news that she not only had an identical twin, but also an older brother and sister.
As a result, scientists became interested in this case, sohow they had the unique opportunity to compare the characteristics of twins using a series of tests to assess intelligence, personality characteristics, mental health and medical history. The results showed that the IQ of the twin raised in the United States was 16 points lower than that of the twin raised in Korea. This contradicts previous studies of monozygotic twins, in which the average IQ difference was no more than seven points.
Surprisingly, the twins demonstratedsignificant differences in cognitive abilities that have been associated with strong genetic influence. The US-raised sister suffered three concussions that may have affected her cognitive abilities.
The general personality of the twins was similar, thatconsistent with data on moderate genetic influence on personality in adulthood. It is noteworthy that both twins clearly have high levels of conscientiousness, indicating that they are both goal-oriented, organized, obedient and strive for achievement.
Surprisingly, this similarity persisted,despite the sisters' very different life experiences and home environments, the researchers say, and highlights the role genetics play in determining a person's temperament.
The life of the twins turned out differently.The girl who stayed in South Korea grew up with her family, in a house full of peace and harmony, and the adopted girl spoke about the tough upbringing, conflicts in the house and the divorce of her parents. But despite this, the grown-up twins showed similar self-esteem scores and very similar mental health profiles.
Finally, the study also shows thatthe twins differed in regards to their cultural ideologies, with the United States-raised twin exhibiting more individualistic attitudes, while the Korean-raised sister had "more collectivist" values.
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