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The whole nurture vs nature debate is a long and ongoing one. Even experts can’t agree on which one holds more value. What they can agree on is that it isn’t one or the other. Nurture and nature are intricately woven in such a way that one does not exist without the other.
Recently, I came across an article referring to identical twins who were separated at the age of 2 and grew up across the world from each other. One twin grew up in Korea and the other was eventually sent to the US and grew up there. The twins were reunited many years later in adulthood and a study was conducted on them.
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.
Nancy L.Segala and Yoon-MiHur in Personality and Individual Differences
Identical twins are about as close as we can get to controlling genetic variation. The differences we can see in these twins can provide some insight into the effect of the environment on their development.
The twin raised in Korea grew up in a happy, harmonious home, whereas the US-based twin had a more turbulent childhood. She lost her family, found a new one, and conflict in her new home resulted in the eventual divorce of her adoptive parents.
Lad Bible
In this case, both twins were raised very differently – in different countries with families with different cultures. The most significant difference between the twins was their IQ scores – the Korean twin scored 16 points higher than her American twin. However, despite their very different upbringing, both twins were similar in personality, their values, and approach to life. Both their self-esteem and mental health profiles were also identical.
Notable is that both twins are distinctively high on conscientiousness, indicating that both are purposeful, well-organised, dutiful, and achievement-striving.
Nancy L.Segala and Yoon-MiHur in Personality and Individual Differences
While it is only a study of one set of twins, it does suggest that we may have more control over intelligence than personality. Intelligence can be nurtured, but personality may be more fixed.