

Beyond Heritability: Twin Studies in Behavioral Research - tokenadult
http://www3.interscience.wiley.com/journal/122587149/abstract?CRETRY=1&SRETRY=0

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tokenadult
It's possible to get past the pay wall on this brand new article

Johnson, W., Turkheimer, E., Gottesman, I., and Bouchard, T. (2009). Beyond
Heritability: Twin Studies in Behavioral Research. Current Directions in
Psychological Science, 18, 4. 217-220.

here:

[http://www.psychologicalscience.org/journals/cd/18_4_inpress...](http://www.psychologicalscience.org/journals/cd/18_4_inpress/Johnson_final.pdf)

The article, by some of the leading researchers on behavioral genetics,
corrects common misconceptions about what "heritability" means. Contrary to
much opinion of persons who have not studied genetics, heritability has
nothing to do with what Sandra Scarr or William Angoff called "malleability,"
how much a trait can be influenced by environmental factors:

"Moreover, even highly heritable traits can be strongly manipulated by the
environment, so heritability has little if anything to do with
controllability. For example, height is on the order of 90% heritable, yet
North and South Koreans, who come from the same genetic background, presently
differ in average height by a full 6 inches (Pak, 2004; Schwekendiek, 2008)."

Using twin studies to look for discordant traits between monozygotic twins
provides some surprising controls on assumptions of genetic determinism in
human behavior:

"In a related vein, intelligence and education are often associated with
healthier lifestyle choices (Deary, Whalley, Batty, & Starr, 2006;
Gottfredson, 2004). Controlling for genetic and shared-environmental
influences, however, Johnson, Hicks, McGue, & Iacono (in press) found that
both higher IQ and greater education were associated with more alcohol and
nicotine use in both sexes at age 24. This suggests that the generally lower
substance use among brighter and better-educated young adults results from
selection on genetic and family influences contributing to an environment
emphasizing both educational attainment and reduced substance use, rather than
from direct application of intelligence and/or education in substance-use
choices."

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dhs
Thanks for digging up this link.

