Thais Fonseca

Health

Researchers analyzed IQ tests of twin sisters who grew up separately

Above average intelligence depends more on external factors than on genetics.  Photo: Pixabay.
Above average intelligence depends more on external factors than on genetics. Photo: Pixabay.

A recently released research points out that the IQ (intelligence quotient) may be more associated with the breeding environment than genetic issues. The result comes from a study carried out by researchers at California State University in partnership with scientists at Kookmin University in Seoul, Korea.

To do this, the researchers analyzed the IQ tests of two identical twin sisters who grew up separately. They were born in Seoul, South Korea, in 1974 and at the age of two a twin was adopted by an American family and taken to live in the USA. Separated in childhood, they were reunited at the age of 26.

They performed a series of tests to assess intelligence, personality profiles, mental health and medical history. The results revealed that the US-raised twin’s IQ was 16 points lower than the Korean-raised sister’s. The result of this research was published in the journal Personality and Individual Differences and contradicts previous studies on twins, which indicated an average IQ difference of up to seven points.

The authors of the study write that “it is impressive that the twins showed substantial differences in cognitive abilities that were associated with a strong genetic influence”, according to an article published in BBC News Brazil. However, researchers reveal that general aspects of the twins’ personality were similar, consistent with studies of genetic influences in adulthood.

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