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Thursday, October 22, 2015

Heritability Coefficients: When Will Text Books Catch Up?


Eric Turkheimer reviewed Jay Joseph's The Trouble With Twin Studies: A Reassessment of Twin Research in the Social and Behavioral Sciences. Heritability is often discussed in psychology classes and textbooks. For example, in Introduction to Psychology texts, heritability coefficients are often discussed for several issues including intelligence and psychological disorders. The Introduction to Psychology text that I use spends two pages discussing the heritability of IQ scores, complete with the ubiquitous figure showing the correlations between twins reared together, twins reared apart, unrelated children raised together, and unrelated children raised apart (Similar graphs were in Intro texts when I was in college!)  One thing I do whenever my classes cover such information, is to emphasize that genes can influence our choice of environment and that environment can influence how genes influence our behavior, so that it is very difficult to disentangle genetic and environmental effects. In all fairness to my Intro text, the authors note this also.

Given Jay Joseph's book and Turkheimer's review, both of which suggest that these coefficients really do not provide much information, is it time to eliminate such discussions from textbooks?

Read the Review
ReviewArsonists at the Cathedral
By Eric Turkheimer
      PsycCRITIQUES, 2015 Vol 60(40)


Andrew Stock

A quote I shared on Moodle, in 2014, as part of your online History and Systems course, Danny:

"A Duke political scientist named Evan Charney and Harvard geneticists Jon Beckwith and Corey Morris examined the flaws in the Alford study—and showed why all the other twin studies on heritability can't possibly show what they purport to show."

I believe the "Alford study" had been purporting to be able to predict how someone would vote based on their genes!

Ask any credible geneticist about heritability ratios - they're old and unhelpful. Epigenetic research is the way forward!

Jay Joseph

As the author of The Trouble with Twin Studies, I am pleased to see that PsycCRITIQUES has set up this online forum to discuss these very important issues. I have written a response to Dr. Turkheimer’s review, which can be found online at

A pdf version can be found at

In addition, my colleagues and I recently published an article on the use of the classical twin method in the social sciences. This article can be found at

I look forward to participating further in the ongoing discussion.

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Editor of PsycCRITIQUES

Danny Wedding, PhD

Chair of Behavioral Sciences,
College of Medicine,
American University of Antigua

Associate Editors of PsycCRITIQUES

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