Sociopolitical Attitudes Through the Lens of Behavioral Genetics: Contributions from Dr Nicholas Martin

2020 ◽  
Vol 23 (2) ◽  
pp. 125-126
Author(s):  
Brad Verhulst
Keyword(s):  
Political Attitudes ◽  
Behavioral Genetics ◽  
Psychological Variables ◽  
Substantial Impact ◽  
Twin Model ◽  
Socially Constructed ◽  
Equal Environments Assumption ◽  
Sources Of Variation ◽  
Equal Environments ◽  
Typical Mode

AbstractProfessor Nicholas (Nick) Martin spearheaded initial investigations into the genetic basis of political attitudes and behaviors, demonstrating that behaviors that are perceived as socially constructed could have a biological basis. As he showed, the typical mode of inheritance for political attitudes consists of approximately equal proportions of variance from additive genetic, shared environmental and unique environmental sources. This differs from other psychological variables, such as personality traits, which tend to be characterized by genetic and unique environmental sources of variation. By treating political attitudes as a model phenotype, Nick Martin was able to leverage the unique pattern of observed intergenerational transmission for political attitudes to reexamine the quintessential assumptions of the classical twin model. Specifically, by creatively leveraging the nuances of the genetic architecture of political attitudes, he was able to demonstrate the robustness of the equal environments assumption and suggest corrections to account for assortative mating. These advances have had a substantial impact on both the fields of political science, as well as behavioral and quantitative genetics.

scholarly journals Twin Studies, Molecular Genetics, Politics, and Tolerance: A Response to Beckwith and Morris

2008 ◽  
Vol 6 (4) ◽  
pp. 793-797 ◽  
Author(s):  
John R. Alford ◽  
Carolyn L. Funk ◽  
John R. Hibbing
Keyword(s):  
Molecular Genetics ◽  
Human Behavior ◽  
Behavioral Genetics ◽  
Twin Studies ◽  
Quarter Century ◽  
Political Orientations ◽  
Equal Environments Assumption ◽  
And Control ◽  
Equal Environments

Beckwith and Morris raise concerns about the value of twin studies for understanding the role of genetics in complex human behavior, but virtually all of their concerns have been raised and rebutted before. When it comes to the equal environments assumption (EEA), the best approach is to test for and control possible violations of the EEA on heritability estimates rather than merely rejecting all empirical evidence because of the possibility of EEA violations. In many respects, since the study of the genetic basis of complex human behaviors now includes many methods in addition to twin studies, Beckwith and Morris's critique applies more to the behavioral genetics of a quarter century ago than to today's multifaceted behavioral genetics. Twin studies establish that there is a sizeable genetic component to political orientations, thereby giving cause to look further at the nature of that role by using other methodologies, including molecular genetics. We conclude by pointing out that the normative implications of the relevance of genes to human behavior are not nearly as worrisome as Beckwith and Morris seem to believe.

The “Equal Environments Assumption” in MZ-DZ Twin Comparisons: an Untenable Premise of Psychiatric Genetics?

1996 ◽  
Vol 45 (3) ◽  
pp. 349-360 ◽  
Author(s):  
A. Pam ◽  
S.S. Kemker ◽  
C.A. Ross ◽  
R. Golden
Keyword(s):  
Mathematical Model ◽  
Behavioral Genetics ◽  
Empirical Studies ◽  
Heritability Estimate ◽  
Operational Definition ◽  
Psychiatric Genetics ◽  
Equal Environments Assumption ◽  
Definition Of ◽  
Scientific Value ◽  
Equal Environments

AbstractThe comparison of MZ-DZ twins in behavioral genetics has produced what seems like irrefutable evidence for the heritability of many psychiatric disorders. But such research depends on the validity of the EEA – the “equal environments assumption” – as an underlying premise. In this paper, several empirical studies which support the EEA are critically reviewed in terms of methodology and the way data has been processed in a mathematical model called “path analysis”. It turns out that studies investigating the EEA appear to be largely inadequate in terms of technique, as well as biased in the inferences drawn. Further, the “heritability” estimate – often taken to mean the influence of trait – specific genes – is merely a statistical abstraction derived from a matrix of correlations; this estimate encompasses many buried environmental effects so that “heritability” does not correspond to any underlying DNA structure. In conclusion, many MZ-DZ pedigree studies have dubious scientific value, given the non-viable premise of the EEA, as well as the misleading operational definition of what has been called “heritability”.

Twins: a test of the equal environments assumption

1990 ◽  
Vol 81 (4) ◽  
pp. 322-326 ◽  
Author(s):  
A. Morris-Yates ◽  
G. Andrews ◽  
P. Howie ◽  
S. Henderson
Keyword(s):  
Equal Environments Assumption ◽  
Equal Environments

scholarly journals Heritability and the Equal Environments Assumption: Evidence from Multiple Samples of Misclassified Twins

2013 ◽  
Vol 43 (5) ◽  
pp. 415-426 ◽  
Author(s):  
Dalton Conley ◽  
Emily Rauscher ◽  
Christopher Dawes ◽  
Patrik K. E. Magnusson ◽  
Mark L. Siegal
Keyword(s):  
Equal Environments Assumption ◽  
Multiple Samples ◽  
Equal Environments

Heredity and Environment in Phoneme Articulation: Hereditary and Environmental Contributions to Articulation Proficiency

1995 ◽  
Vol 44 (2) ◽  
pp. 63-73
Author(s):  
W. E. Dixon ◽  
A. P. Matheny ◽  
S. R. Mohr
Keyword(s):  
Factor Analysis ◽  
Multiple Regression ◽  
Behavioral Genetics ◽  
Environmental Influences ◽  
Individual Factors ◽  
Factor Scores ◽  
Genetic Components ◽  
Sources Of Variation ◽  
Regression Techniques ◽  
The Individual

AbstractLarge twin samples and recent applications of multiple regression techniques to behavioral genetics methodology makes possible evaluation of genetic and environmental contributions to the articulation proficiency of individual phonemes. Factor analysis of the articulation scores from 256 MZ and DZ twins and 124 of their non-twin siblings (all children ranged from 2; 11 to 9; 8 years) were conducted to reduce a 50-item articulation test to a more manageable set of five articulation factors. The twins' factor scores were then analyzed using multiple regression procedures to determine the extent to which the individual factors resulted from genetic and/or environmental influences. The /r/ and /∫, t∫, dƺ/ factors were found to have strong genetic components, while the /l, j, w/ factor was found to be strongly influenced by environmental sources of variation.

Twin Studies of Political Behavior: Untenable Assumptions?

2008 ◽  
Vol 6 (4) ◽  
pp. 785-791 ◽  
Author(s):  
Jon Beckwith ◽  
Corey A. Morris
Keyword(s):  
Molecular Genetic ◽  
Genetic Research ◽  
Twin Studies ◽  
First Century ◽  
Behavioral Traits ◽  
Political Ideologies ◽  
Equal Environments Assumption ◽  
Twin Method ◽  
Genetic Techniques ◽  
Equal Environments

Using the “classical twin method,” political scientists John Alford, Carolyn Funk, and John Hibbing conclude that political ideologies are significantly influenced by genetics, an assertion that has garnered considerable media attention. Researchers have long used human twins in attempts to assess the degree of genetic influence on various behavioral traits. Today, this methodology has been largely replaced in favor of contemporary molecular genetic techniques, and thus heritability studies have seen a diminishing role in behavioral genetic research of the twenty-first century. One important reason the twin method has been superseded is that it depends upon several questionable assumptions, the most significant of which is known as the equal environments assumption. Alford, Funk, and Hibbing argue that this crucial assumption, and thus their conclusion, holds up under empirical scrutiny. They point to several studies in support of this assumption. Here, we review the evidence presented and conclude that these attempts to test the equal environments assumption are weak, suffering significant methodological and inherent design flaws. Furthermore, much of the empirical evidence provided by these studies actually argues that, contrary to the interpretation, trait-relevant equal environments assumptions have been violated. We conclude that the equal environments assumption remains untenable, and as such, twin studies are an insufficient method for drawing meaningful conclusions regarding complex human behavior.

The Genetics of Political Attitudes and Behavior: Claims and Refutations

2010 ◽  
Vol 12 (3) ◽  
pp. 200-217 ◽  
Author(s):  
Jay Joseph
Keyword(s):  
Genetic Factors ◽  
Political Attitudes ◽  
Molecular Level ◽  
Twin Studies ◽  
Theoretical Assumption ◽  
Study Results ◽  
Twin Method ◽  
And Behavior ◽  
Attitudes And Behavior ◽  
Equal Environments

Some political scientists have argued in recent years that twin research shows that genetic factors play an important role in shaping political attitudes, ideologies, and behavior. Moreover, some researchers claim to have identified genes for political traits at the molecular level. The author argues that the main theoretical assumption of the twin method, which holds that monozygotic and dizygotic twin pairs experience equal environments, is untenable. Therefore, the results of twin studies can be completely explained by nongenetic factors. The author also argues that recent gene discovery claims in political science are unlikely to be replicated. He concludes that because genetic interpretations of twin study results are confounded by environmental factors, political scientists have no reason to revise previous socialization theories of political traits.

scholarly journals Are Political Orientations Genetically Transmitted?

2005 ◽  
Vol 99 (2) ◽  
pp. 153-167 ◽  
Author(s):  
JOHN R. ALFORD ◽  
CAROLYN L. FUNK ◽  
JOHN R. HIBBING
Keyword(s):  
Genetic Factors ◽  
Political Attitudes ◽  
Behavioral Genetics ◽  
Party Identification ◽  
Monozygotic Twins ◽  
The United States ◽  
Genetic Heritability ◽  
Political Orientations ◽  
Methodological Approaches ◽  
Analyze Data

We test the possibility that political attitudes and behaviors are the result of both environmental and genetic factors. Employing standard methodological approaches in behavioral genetics—specifically, comparisons of the differential correlations of the attitudes of monozygotic twins and dizygotic twins—we analyze data drawn from a large sample of twins in the United States, supplemented with findings from twins in Australia. The results indicate that genetics plays an important role in shaping political attitudes and ideologies but a more modest role in forming party identification; as such, they call for finer distinctions in theorizing about the sources of political attitudes. We conclude by urging political scientists to incorporate genetic influences, specifically interactions between genetic heritability and social environment, into models of political attitude formation.

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