Twins – Korean that is….

By Razib Khan | August 29, 2007 3:37 am

Genetic and environmental contributions to prosocial behaviour in 2- to 9-year-old South Korean twins:

…The best-fitting model indicated that 55%…of the variance in the 2- to 9-year-olds’ prosocial behaviour was due to genetic factors and 45%…was due to non-shared environmental factors. It is concluded that genetic and environmental influences on prosocial behaviour in young South Koreans are mostly similar to those in western samples.

This is the “standard” finding, most of the variation in behavior is due to genes or non-shared environment. In The Nurture Assumption Judith Rich Harris posited that the “non-shared environment” basically meant peer groups. Remember though that this is measuring a component of variance, so it applies to traits which vary throughout a population.

  • John Emerson

    I know of one case of a pair of Eurasian twins who were separated after their parents’ divorce, one being raised as an Indian and one as an American. That would be an interesting twin study!
    It probably didn’t happen, but it might be worth looking for separated twins among the 160,000 or so Korean babies adopted to the US (sometimes called “Holt babies”). I doubt that the 55/45 proportion would hold up with babies raised in entirely different cultures. In a lot of twin studies the environmental and the genetic difference are both pretty small. Families separated by warfare or emigration might be another place to look. I used to know a punkish Chinese-American woman whose first cousins were all Chinese villagers.

  • Jason Malloy

    No twins, but we can compare if those Holt babies act more like little Koreans or like little Americans.
    In some ways they are more Korean (weight, IQ), in some ways they are more American (favorite movies/music, language) and in some ways they are in between (temperament, drinking).

  • Jason Malloy

    Oh, I didn’t notice that was a Rushton paper. Here’s another recent one.


Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

Gene Expression

This blog is about evolution, genetics, genomics and their interstices. Please beware that comments are aggressively moderated. Uncivil or churlish comments will likely get you banned immediately, so make any contribution count!

About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at


See More


RSS Razib’s Pinboard

Edifying books

Collapse bottom bar