Identical Twins Separated at Birth

For decades now the psycho world has shown some very serious interest in identical twins separated at birth. You see, when trying to assess how much of development was built into one's genes and how much was culturally imposed, studies of identical twins, separated at birth was clearly the way to go.

So, nature vs. nurture, an interesting question, one that usually concludes that far more of your development is built into your genes, far less is determined by culture.

Anyway, researcher Nancy Segal examines a single case where the identical twins separated at birth were brought up in radically different cultures. That is, where one was brought up in America while the other was brought up in South Korea.

Dare I mention, because this is what you are thinking, that this is a singular case, so it must have the word “anecdotal” affixed to it. And, one wonders how much the study took into account whether the Korean child brought up in America was brought up by Korean-American parents, and in what community. 

Here are some conclusions, via PsyPost:

The twin who remained in South Korea was raised in a more supportive and cohesive family atmosphere. The twin who was adopted by the U.S. couple, in contrast, reported a stricter, more religiously-oriented environment that had higher levels of family conflict.

One does not know whether the child brought up in Korea was brought up in a religious environment. Since Korea is a notably Christian country, this would have been useful to know.

But, we certainly accept that the Korean family atmosphere was more cohesive, while the American family was more chaotic.

The first and most marked difference lay in cognitive ability. The child brought up in South Korea was considerably more intelligent. Again, we do not know about the education the American child received, though we know that as a general rule it is substandard. And we know that American children tend to score poorly on international tests:

The researchers found “striking” differences in cognitive abilities. The twin raised in South Korea scored considerably higher on intelligence tests related to perceptual reasoning and processing speed, with an overall IQ difference of 16 points.

As for values, the twin from South Korea had more communitarian values, while the American twin was more individualistic. Nothing very surprising there:

In line with their cultural environment, the twin raised in the United States had more individualistic values, while the twin raised in South Korea had more collectivist values.

Personality traits, however, seem to be inscribed in each twin’s genes:

However, the twins had a similar personality. Both scored high on measures of conscientiousness and low on measures of neuroticism. They also had a similar level of satisfaction with their job, even though their occupations were quite different — a government administrator and a cook. The twins also had similar mental health profiles and had identical scores on the measure of self-esteem.

Presumably, the higher IQ twin, from South Korea was a government administrator while the lower IQ twin, from America was working as a cook.