Left or Right? Sources of Political Orientation: The Roles of GeneticFactors, Cultural Transmission, Assortative Mating, and Personality

Christian Kandler, Wiebke Bleidorn, and Rainer RiemannBielefeld University

In this study, we used an extended twin family design to investigate the influences of genetic and culturaltransmission as well as different sources of nonrandom mating on 2 core aspects of political orientation:acceptance of inequality and rejecting system change. In addition, we studied the sources of phenotypiclinks between Big Five personality traits and political beliefs using self- and other reports. Data of 1,992individuals (224 monozygotic and 166 dizygotic twin pairs, 92 unmatched twins, 530 spouses of twins,268 fathers, and 322 mothers) were analyzed. Genetically informative analyses showed that politicalattitudes are genetically but not environmentally transmitted from parents to offspring and that asubstantial proportion of this genetic variance can be accounted for by genetic variance in personalitytraits. Beyond genetic effects and genotypic assortative mating, generation-specific environmentalsources act to increase twins’ and spouses’ resemblance in political beliefs. The results suggest multiplesources of political orientations in a modern democracy.

Keywords: extended twin family study, personality, political attitudes, assortative mating, social homog-amy

Supplemental materials: http://dx.doi.org/10.1037/a0025560.supp

Since the French Revolution in 1789, political parties and ideasof modern democracies are often described on a one-dimensionalpolitical spectrum from left to right. Regarding the simplest dif-ferentiation, progressive, communistic, and liberal positions areoften arranged on the left wing, whereas fascist, capitalist, andconservative orientations are usually classified as being on theright side (Jost, Federico, & Napier, 2009). As a single left–rightaxis appears to be insufficient to describe the existing variation inpolitical beliefs and fails to capture significant heterogeneousaspects of ideology, researchers have often included additionaldimensions, for example, humanitarianism and nationalism (Fer-guson, 1941), radicalism and tough-mindedness (Eysenck, 1956),dogmatism (Rokeach, 1960), and cultural and economic policydomains (Duckitt, Wagner, du Plessis, & Birum, 2002; Eysenck,1976), suggesting a two- or multidimensional structure to describepolitical orientation. However, some dimensions rather reflectcontent-free behavioral styles (e.g., tough-mindedness or dogma-tism) and are orthogonal to the left–right spectrum (Greenberg &Jonas, 2003; Jost et al., 2009).

Core Aspects of Left–Right Ideology

In recent years, a two-dimensional structure of political orien-tations has become established (Evans, Heath, & Lalljee, 1996; fora review, see Jost et al., 2009). One dimension captures attitudestoward equality versus inequality, whereas the other reflects po-litical opinions toward social and system change versus tradition.These dimensions are quite similar to the cultural and economicpolicy domains proposed by Eysenck (1976). In terms of left–rightdifferentiation—which Jost (2006) referred to as liberalism–conservatism in the United States1—left-oriented people, on theone hand, hold more favorable attitudes toward minority groups,question the status quo, and seek egalitarian reforms. Right-orientated people, on the other hand, favor the status quo, servesocial control functions, and accept inequality in society. In anutshell, left-wing people prefer change and equality, whereasright-wing people prefer stability and hierarchy (see Figure 1).

Suggested as core aspects of political orientation (Jost, 2006),the two dimensions acceptance of inequality and resistance tochange are factor-analytic distinct but often positively interrelated,at least in individualistic countries (Hofstede, 1984). That is, “toresist change in general has often meant resisting increased effortsat egalitarianism” (Jost, Kruglanski, Glaser, & Sulloway, 2003, p.343). Previous research indicated that people who prioritize tradi-tionalism and inequality vote more often for conservative andright-wing parties (Barnea & Schwartz, 1998; Jost, 2006). The

1 The common political understanding of left and right or liberalism andconservatism in Germany is not exactly the same as in the United States(Greenberg & Jonas, 2003). For the differentiation of left and right orien-tations in our study, we adopted the American understanding to accomplisha common scientific basis.

This article was published Online First October 10, 2011.Christian Kandler, Wiebke Bleidorn, and Rainer Riemann, Department

of Psychology, Bielefeld University, Bielefeld, Germany.We thank Wendy Johnson and Alexander Weiss for their helpful com-

ments on a previous version of this article.Correspondence concerning this article should be addressed to Christian

Kandler, Department of Psychology, Bielefeld University, Universitatsstr.25, D-33615 Bielefeld, Germany. E-mail: christian.kandler@uni-bielefeld.de

Journal of Personality and Social Psychology © 2011 American Psychological Association2012, Vol. 102, No. 3, 633–645 0022-3514/12/$12.00 DOI: 10.1037/a0025560

633

other way around, people who favor progression and egalitarian-ism vote more often for liberal and left-wing parties (Barnea &Schwartz, 1998; Jost, 2006). Acceptance of inequality predictscollective action in groups and group identification (Deaux, Reid,Martin, & Bikmen, 2006). Recently, criterion-related validity wasalso demonstrated for implicit measures of the two core aspects(Jost, Nosek, & Gosling, 2008).

Situational and Dispositional Influences on PoliticalOrientation

A broad body of literature indicates that ideological orientationsare transmitted from parents to offspring, are influenced by peersand reference groups, and are also affected by life events such asacts of terrorism (e.g., 9/11) or traveling in foreign countries andcultures (Jost et al., 2009; Leonard, 1964; Rosenblatt, Greenberg,Solomon, Pyszczynski, & Lyon, 1989). Experimental studies haveshown that social and economic threats can increase social intol-erance, system justification, and right-wing responding (McCann,2008; McGregor, Zanna, Holmes, & Spencer, 2001).

However, people’s political orientations depend not only onsituational factors and the contexts in which they live but also onwho they are, that is, their individual traits. Right-oriented people“are, on average, more rigid and closed-minded” (Jost, 2006, p.661) than left-oriented people. Not surprisingly, right-orientedpeople score higher on measures of dogmatism; needs for struc-ture, closure, and order; and Conscientiousness (Carney, Jost,Gosling, & Potter, 2008). Left-oriented people are “more open-minded in their pursuit of creativity, novelty, and diversity” (Jost,2006, p. 664). They were found to score higher on tender-mindedness, a facet of Agreeableness (Jost, 2006), and all facets ofOpenness to Experience (Carney et al., 2008).

Behavioral genetic studies have shown that political attitudes(e.g., gay rights) and even behavior (e.g., voter turnout) are genet-ically influenced, with heritability estimates ranging between 20%and 70% (e.g., Alford, Funk, & Hibbing, 2005; Bell, Schermer, &Vernon, 2009; Bouchard et al., 2003; Fowler & Schreiber, 2008;Hatemi et al., 2010). In recent years, there has been a growinginterest in the amount and kind of genetic effects on political

orientations, in particular on those genetic influences that areshared with other psychological characteristics such as the BigFive personality traits (Carney et al., 2008; Mondak & Halperin,2008; Vecchione & Caprara, 2009).

Political Orientation and the Role of Personality

The Big Five personality traits (Neuroticism, Extraversion,Openness to Experience, Agreeableness, and Conscientiousness)have been described as genetically anchored basic tendencies(McAdams & Pals, 2006; McCrae & Costa, 2008). These traits areoften viewed as mediators of genetic differences affecting an arrayof socially relevant attributes, such as political beliefs and behav-ior, because they are cross-culturally valid, largely stable, andstrongly genetically influenced (Kandler, Bleidorn, et al., 2010;Kandler, Riemann, Spinath, & Angleitner, 2010; McCrae & Costa,2003; McCrae, Terracciano, & 78 Members of the PersonalityProfiles of Cultures Project, 2005). Going beyond a mere media-tion, the five-factor theory (FFT; McCrae & Costa, 2008) regardssocial attitudes as characteristic adaptations. According to thisview, they result from the interplay between genetically basedpersonality traits (i.e., basic tendencies: the five domains andrespective facets) and individual-specific as well as culture-specific environments. As an implication of FFT, the vast majorityof genetic variance in measures of attitudes should be accountedfor by the genetic factors on personality traits.

Alford and Hibbing (2007) proposed a contrary position andgrounded their claims on the fact that the overall correlationsbetween personality traits and political attitudes were only mod-erate in magnitude. They concluded that personality traits andpolitical attitudes are better described as systematically related butdistinct dispositions of human behavior. From this perspective,political attitudes are not subordinate to personality traits butshould have their own biological basis.

What is the story the empirical results tell? A recent studyprovided support for FFT with regard to political orientation, inwhich the authors posited “that personality traits play a significantrole in shaping political orientation, but do so largely indirectly,via an intermediary layer of characteristic adaptations” (Lewis &Bates, 2011, p. 556). Relying on phenotypic variables, the authorscould not disentangle genetic from environmental contributions tothe links in this study. To our knowledge, only two studies haveexamined the genetic links between political attitudes and person-ality traits. One study focused on the links between a person’sgeneral ideology as well as more specific political attitudes (e.g.,gender, outgroup, and punishment) and Eysenck’s Psychoticism–Extraversion–Neuroticism model. Results suggested that geneticinfluences affecting individual differences in these broad traitdimensions (primarily psychoticism) do also affect political atti-tudes (Verhulst, Hatemi, & Martin, 2010). The other study pointedto substantial genetic but weak environmental links between so-ciability—a temperament trait linked to Extraversion (Hampson,Andrews, Barckley, & Peterson, 2007)—and attitudes towardequality (Olson, Vernon, Harris, & Jang, 2001).

To date, no genetically informative study has examined theunderlying sources of the relations among the Big Five personalitytraits and core aspects of political orientation. Yet, investigatingtheir genetic links seems to be both empirically indicated andtheoretically reasonable. Empirically, political orientations were

Le� Right

Rejec�nginequality(Egalitarianism)

Rejec�ng systemchange(Tradi�onalism)

Advoca�ngsystem change(Progression)

Acceptance ofinequality(Ethnocentrism)

Figure 1. The figure illustrates the left–right orientations with regard tothe two dimensions of attitudes toward social equality versus inequalityand toward system change versus stability (Jost et al., 2009).

634 KANDLER, BLEIDORN, AND RIEMANN

mostly found to be linked to Openness, Conscientiousness, andAagreeableness (Carney et al., 2008; Gerber, Huber, Doherty,Dowling, & Ha, 2010; Jost, 2006). Theoretically, it seems reason-able to assume that the broad domains of Conscientiousness,Agreeableness, and Openness are promising candidates that mightmediate the genetic effects on the two core aspects of politicalorientation (McCrae & Costa, 2008; Jost et al., 2009).

Moreover, previous studies on the relations among personalityand political attitudes, positions, and behaviors have exclusivelyrelied on respondents’ self-reports (e.g., Duckitt & Sibley, 2010;Gerber et al., 2010; Mondak, Hibbing, Canache, Seligson, &Anderson, 2010). Self-reports may reflect accurate measures ofpersonality and political attitudes but could be biased by responsestyles, self-deception, and impression management due to respon-dent’s values or social norms (i.e., social desirability; Paulhus &John, 1998). As a consequence, the links between self-reportedpersonality and political beliefs may not only reflect substantialrelations but may also be due to method bias. Therefore, additionalmeasurement methods (e.g., peer reports or observer ratings)should be used to validate the links across different measures,because correlations between peer reports on personality and self-reports on political orientation cannot be accounted for by self-rater biases.

Political Orientation and the Role of AssortativeMating

Beyond the links between personality traits and political orien-tation, previous research identified some interesting differencesbetween personality and political attitudes. Compared with per-sonality traits for which environmental effects shared by relativesare weak, if at all significant (estimates range between 0% and10%; for a review and a meta-analysis, see Bouchard & Loehlin,2001; Johnson, Vernon, & Feiler, 2008), genetically informativetwin studies have consistently shown shared environmental influ-ences on political attitudes up to 50% (Alford et al., 2005; Bell etal., 2009; Verhulst et al., 2010). These environmental influencesshared by twins may in part reflect the contribution of the assor-tative mating of twins’ parents to their offsprings’ similarity.However, assortative mating can take various forms. That is,environmental as well as genetic factors may play a role inspouses’ resemblance and, thus, estimates of shared environmentalinfluences on offspring might partially reflect genetic factors (Al-ford et al., 2005).

It is well-known that assortative mating is weak for personalitytraits but substantial for attitudes. Spouse correlations for person-ality traits usually range between �.10 and .25 (for reviews, seeJohnson et al., 2008; Watson et al., 2004). For political attitudes,Alford et al. (2005; see also Hatemi et al., 2010) found moderateto substantial spouse correlations, ranging between .25 and .65 (.41on average). Indeed, when the impact of parental correlation waspartialed out, the averaged estimates of shared environmentaleffects decreased from 22% to 11% and genetic effects increasedfrom 43% to 53%. This result supports the contribution of geneticfactors to spousal similarity in political attitudes (i.e., genotypicassortative mating). Genotypic assortative mating in parents oftwins increases genetic correlations of dizygotic (DZ) but not of(genetically identical) monozygotic (MZ) twins. This leads todecreased differences between MZ and DZ twins’ levels of phe-

notypic correlations. As a consequence, estimates of shared envi-ronmental factors that do not take genotypic assortative matinginto account would be overestimated and heritability would beunderestimated in studies of twins.

However, spouse similarity may also result from social pro-cesses. Spouse correlation due to actual shared environments (e.g.,shared social background and cultural environments) is termedsocial homogamy (Watson et al., 2004). To the degree to whichassortative mating results from social homogamy, shared environ-mental factors may effectively contribute to similarity betweenparents and offspring (i.e., vertical cultural transmission) as well asamong offspring. As a consequence, both MZ and DZ correlationsincrease. In this case, estimates of shared environmental factors instudies of twins would actually reflect shared environmental in-fluences and heritability estimates would not be distorted.2 Fur-thermore, similarity between spouses may also result from spouse-specific sources (e.g., common habits and friends) and socialinteraction effects (Caspi, Herbener, & Ozer, 1992), which maynot contribute to offspring’s resemblance and, thus, would notcontribute to MZ and DZ twin correlations.

To our knowledge, no study has investigated the different mech-anisms potentially underlying phenotypic assortment in basic po-litical attitudes. Distinguishing among the different potentialsources of phenotypic spouse correlations (i.e., genotypic assorta-tive mating, social homogamy, or spouse-specific effects) requiresan inclusion of data from spouses of MZ and DZ twins to thestandard twin design. Genotypic assortative mating (i.e., spousecorrelation due to shared genetic factors) would be indicated by (a)a larger correlation between a twin and the cotwin’s spouse forgenetically identical MZ twins than for fraternal DZ twins and (b)a larger correlation between MZ twins’ spouses than DZ twins’spouses. Genotypic assortative mating necessarily implies that theparticular trait is heritable. Yet, the fact that a trait is heritable doesnot necessarily imply that the sources of assortative mating aregenetic. Social homogamy is attributable to the shared environ-ments of twins and spouses. It would lead to (a) a correlationbetween wife and husband equal to that between a twin and thecotwin’s spouse, (b) a correlation between an MZ twin and his orher cotwin’s spouse identical to the one between a DZ twin and hisor her cotwin’s spouse, and (c) a correlation between spouses oftwins that does not differ between MZ and DZ twins. Finally,social influences on spouses may be unique to partners and wouldbe indicated by significant correlations of spouses but zero corre-lations (a) between twins and their cotwins’ spouses and (b)between spouses of twins.

The differentiation between genetic and environmental spouseresemblance is crucial because each mechanism is associated withdifferent implications: Genotypic assortative mating increases thegenetic variation in a population, whereas social homogamy andspouse-specific effects highlight the importance of social andcultural factors or reciprocal effects of partners themselves.

2 Estimates of social homogamy can be confounded with genetic effectsif population stratification exists for the focused trait in the concerningsociety. Population stratification increases the genetic resemblance withina family and differences between families because of nonrandom matingbetween subgroups in the population, often due to their physical separation.

635SOURCES OF POLITICAL ORIENTATION

Current Study

In the present study, we aimed to address two issues that have notbeen studied before. First, we estimated the genetic and environmen-tal sources of two dimensions of political orientation (i.e., rejectingsystem change and acceptance of inequality) by using an extendedtwin family design (twins, parents of twins, and partners of twins),taking the three sources of spouse correlation—genotypic assortativemating, social homogamy, and spouse-specific effects—into account.Second, we investigated the contribution of Big Five personality traitsin accounting for genetic variance in political dimensions. We usedmultiple informants (self- and other reports on personality) for vali-dating the links between personality and political dimensions acrossmethods of measurements. Complete genetic overlap would supportFFT (McCrae & Costa, 2008). Otherwise, personality traits and po-litical attitudes are better described as systematically related but dis-tinct dispositions of human behavior (e.g., Alford & Hibbing, 2007).

Method

Participants

We analyzed data of twins reared together, their parents, andtheir spouses from the Jena Twin Study of Social Attitudes(Stö�el, Kampfe, & Riemann, 2006). The sample consisted of 872twins, including 448 MZ (224 pairs), 332 DZ (166 pairs), and 92unmatched (UM) twins (data available only for one twin sibling).Participants ranged in age from 17 to 82 years (M � 34.30 years,SD � 13.63); 646 of the participants were women (74%). Thesample was heterogeneous with regard to education and occupa-tion (Stö�el et al., 2006).

Procedure

Twins provided self-reports on their personality and political atti-tudes. In addition, twins provided reports on the attitudes of theircotwins. For 86% of the twins, at least one well-informed acquain-tance (e.g., friends, colleagues, and spouses) provided a peer report ofthe twin’s personality (N � 748; note that each twin was rated bydifferent peers than his or her cotwin was). For the present study, peerratings were averaged, resulting in one peer report per individual.Furthermore, 530 spouses (61%), 268 fathers (61%), and 322 mothers(74%) of twins provided self-reports on their political attitudes.

Measures

We measured the two core aspects of political orientation usingeight bipolar items based on the content of the above-mentionedliterature addressing the left–right differentiation (see Table 1). UsingSPSS (Levesque, 2007), we ran principal component analyses (PCA)with minimum average partial tests for determining the number ofcomponents (O’Connor, 2000). In line with previous research (e.g.,Jost, 2006), PCA yielded two dimensions reflecting attitudes towardsocial equality versus inequality and change versus stability (i.e.,acceptance of inequality [AI] and rejecting system change [RC]; seeTable 1). The two dimensions accounted for 45% (fathers’ self-reports) to 49% (twins’ self-reports) of variance. On the basis of theresults of the PCA with promax rotation, we computed factor scoresand scale scores (i.e., sum scores). As also shown in Table 1, the twodimensions were positively correlated, indicating a positive interrela-

tion to the dimension of the left–right ideology (Jost et al., 2009).However, the correlations were not large enough to consider one-dimensional measures of political orientation. We used scale scores inthe following analyses. Internal consistencies were, on average, � �.59 for acceptance of inequality (Items 2, 4, and 5) and � � .61 forrejecting system change (Items 1, 3, 6, 7, and 8). Correlations betweenself- and cotwin reports as indices of quasivalidity were .27 for AI(.30 for MZ and .23 for DZ twins) and .59 for RC (.65 for MZ and .51for DZ twins).3

We measured the Big Five personality traits by the GermanNEO Personality Inventory—Revised (NEO-PI–R; Costa & Mc-Crae, 1992; Ostendorf & Angleitner, 2004), which consists of 240items for mapping personality on 30 facets and five broad dimen-sions: Neuroticism, Extraversion, Openness, Agreeableness, andConscientiousness. Psychometric properties of scale scores andgenetic analyses were presented previously (Kandler, Riemann, &Kampfe, 2009). For the present analyses, we used factor scores ofthe Big Five dimensions based on the NEO-PI–R facets using theAnderson–Rubin method (Anderson & Rubin, 1956). This proce-dure guarantees orthogonality of the Big Five personality domains.As age and sex differences can bias the twin correlations, twins’reports and peer reports were corrected for sex differences, linearas well as quadratic age effects, and Sex � Age interaction effectsusing a regression procedure (McGue & Bouchard, 1984). Allvariables were standardized, followed by the mean and standarddeviation.

Analyses

We calculated phenotypic correlations for family relationshipsand the associations between personality domains and politicaldimensions. Missing values were handled by pairwise deletion.For all genetic analyses, we estimated variance–covariance matri-ces by using expectation maximization procedures for handlingmissing data (Little & Rubin, 2002). These matrices were analyzedby fitting genetically informative structural equation models de-scribed below via maximum likelihood using the statistical soft-ware package Mx (Neale, Boker, Xie, & Maes, 2003).

Estimating the sources of variance in dimensions of politicalorientations, we analyzed data from MZ and DZ twin pairs simul-taneously with data from their parents and spouses. That is, wetested an extended twin family model (see Figure 2). The differ-ence in genetic relatedness between MZ and DZ twin pairs formsthe basis to estimate the amount of variance attributable to geneticand environmental influences. Genetic variance can be decom-posed into additive genetic variance (A) and nonadditive geneticvariance due to allelic dominance deviation within gene loci (i.e.,dominance effects, D) or allelic dominance deviation betweengene loci (i.e., epistatic effects, I). Environmental variance can bedecomposed into variance due to environmental factors that act tomake twins similar (i.e., shared environmental effects, C) andenvironmental factors that act to make twins different (i.e., non-shared environmental effects, E). Adding data from parents of

3 We used the term quasivalidity because self- and cotwin reports are notindependent measurements because of the genetic relatedness of twins. Asa consequence, convergence between cotwin reports and self-reports waslarger for MZ than for DZ twins.

636 KANDLER, BLEIDORN, AND RIEMANN

twins increases the power to detect variance due to nonadditivegenetic effects in the presence of additive genetic and sharedenvironmental effects; it also reduces parameter biases (Heath,Kendler, Eaves, & Markell, 1985). In an extended twin familydesign, vertical cultural transmission from parents to offspring(maternal transmission, m, and paternal transmission, f) and twin-specific shared environmental influences (s) as specific forms ofshared environmental effects (C) can be distinguished from eachother.

An extended twin family model also allows the consideration ofparents’ resemblance with regard to the phenotype of interest (�).The inclusion of spouses of MZ and DZ twins additionally allowsfor distinguishing between the sources of nonrandom mating, thatis, genotypic assortative mating (�A), social homogamy (�C), orspouse-specific effects (�E). The entire variance decomposition ofthe full model used in this study is presented in Table 2. Thismodel assumes the absence of gene–environment correlations andGene � Environment interactions as well as the absence of pop-ulation stratification for the focused variables. As genetic domi-nance effects cannot be estimated in addition to epistatic effectsand effects of twin-specific environments, different model modi-fications were fitted to the data, that is, (a) a model allowing forgenetic dominance but not epistatic effects (i � 0) and (b) a modelallowing for epistatic and no genetic domiance effects (d � 0). Inaddition, we tested reduced models, for example, (a) a modelallowing for vertical cultural transmission only (fixing a, i, d, and�A to zero) and (b) a model allowing for genetic transmission only(fixing m and f to zero).

Addressing the second aim of our study, we estimated thecorrelations between Big Five personality traits and dimensions ofpolitical orientations and validated these associations across meth-ods of measurement (i.e., between peer reports on personality andself-reports on political orientations). The overall magnitude ofgenetic and environmental variance in political attitudes that canbe explained by all Big Five personality traits was estimated byfitting a six-variable twin model known as Cholesky decomposi-tion to the data (see Figure 3; see also Neale & Maes, 2004, formore details).

This model assumes the absence of nonadditive genetic effects,because both shared environmental and nonadditive genetic influ-ences cannot be estimated simultaneously in samples of reared-together MZ and DZ twins. However, models that allow foradditive genetic influences provide a good estimation of broad-sense heritability that will generally include nonadditive geneticeffects (Hill, Goddard, & Visscher, 2008). For model parsimony,we also assumed the absence of shared environmental effects onlyfor personality, because these influences have usually been foundto be small or negligible for the Big Five (Johnson et al., 2008;Kandler, Riemann, et al., 2010). In addition to assessing the overallvariance accounted for by all personality traits, we convertedgenetic and environmental path coefficients between specific per-sonality traits and political dimensions into genetic and environ-mental correlations.

For each of the structural equation model analyses describedabove, we evaluated the overall model by the root-mean-squareerror of approximation (RMSEA � .05 indicates a good andRMSEA � .08 indicates an acceptable fit). The significance ofmodel parameters was evaluated by maximum likelihood–based95% confidence intervals and the chi-square difference test inwhich nested models with more parameters were compared withmodels with fewer parameters. Akaike’s information criterion(AIC; Akaike, 1987) was used for descriptive comparisons be-tween nonnested models, such as the models allowing for domi-nance effects versus epistatic effects (the smallest AIC valueindicates the model that has the best combination of model fit andmodel parsimony).

Results

We calculated twin, mother–offspring, father–offspring, andspouse correlations as well as correlations between spouses and cot-wins and correlations between spouses of twins (see Figure 4; see alsothe online supplemental material). These correlations provided a firstand rough insight into the contributions of genetic and environmentalfactors as well as the sources of nonrandommating. For example, MZ

Table 1Promax Rotated Factor Loadings of Self-Ratings on Political Orientations for Different Twin Family Member Subsamples

Items

Twins (N � 872) Partners (N � 530) Fathers (N � 268) Mothers (N � 322)

AI RC AI RC AI RC AI RC

Rebelliousness–conformity �.25 .54 �.41 .56 �.19 .60 �.07 .67Pro–contra equality among groups .71 .00 .68 �.14 .71 .04 .61 .01Pacifism–militarism .22 .59 .25 .56 .32 .40 .29 .55Tolerance–intolerance .75 �.21 .75 �.24 .73 �.16 .65 �.17Pro support–rejection of minority .63 .22 .56 .18 .70 .05 .78 �.03Left–right .12 .63 .46 .48 .23 .48 .18 .56Pro lenity–law and order �.10 .74 .11 .72 .08 .66 .05 .75Contra patriotism–patriotism .01 .67 �.04 .75 �.13 .79 �.17 .75

Pearson correlations

Factor scores .23� .29� .17� .12Scale scores .26� .36� .27� .25�

Note. AI � acceptance of inequality; RC � rejecting system change. Factor loadings greater than or equal to .40 are shown in bold.� p � .05.

637SOURCES OF POLITICAL ORIENTATION

twin correlations were larger than DZ twin correlations, indicatinggenetic influences; DZ twin correlations were larger than parent–offspring correlations, indicating twin-specific shared environmentaleffects or nonadditive genetic effects; and the positive spouse corre-lations pointed to nonrandom mating. Genotypic assortative matingwas indicated for RC (i.e., larger twin–cotwin’s spouse correlationsfor MZ than DZ twins; see Figure 4), whereas social homogamy wasindicated for AI (i.e., no marked differences of twin–cotwin’s spousecorrelations between MZ and DZ twins; see Figure 4). In addition,spouse correlations were larger than twin–cotwin’s spouse correla-tions for both AI and RC, suggesting an additional influence ofspouse-specific effects on spouse similarity.

Model fitting results are presented in Table 3. For both AI andRC, the AIC indicates that Model 2 (allowing for i2 instead of d2)provided the better model fit. Furthermore, a reduced model al-lowing for additive genetic, shared, and environmental variance, aswell as social homogamy and spouse-specific effects, describedthe family data of AI best. In the case of RC, a more complexmodel in which genotypic assortative mating and nonadditivegenetic effects additionally contributed to the variance was themodel that fitted the data best.

Before we examined the sources of relations between personal-ity traits and the two core aspects of political orientation, we firstcalculated phenotypic correlations for all combinations of mea-surement methods (rP in Table 4). We found significant (negative)correlations between AI and the two personality domains of Open-ness and Agreeableness for both self- and peer reports. For RC,moderate positive correlations with Conscientiousness and Extra-version but substantial negative correlations with Openness wereconsistent across measurement methods.4

We ran multivariate genetic analyses to further examine thesources of these associations. Model fitting results (see Table 5)suggested that the phenotypic overlap between personality traitsand political dimensions is largely mediated by genetic factors.Most of the genetic variance in political dimensions could be

4 As we exclusively focused on the Big Five, genetic effects on morespecific personality facets independent of the genetic effects on the fivebroad domains (Kandler, Riemann et al., 2010) could account for addi-tional genetic variance in ideological dimensions. Therefore, we computedcorrelations between the two political dimensions and the 30 personalityfacet residuals, for which common variance with Big Five personality traitswere partialed out by regression procedure. Correlations were generallysmall and ranged between �.15 and .12, with only 16 of 120 correlations(30 facets � 2 political attitudes � 2 methods of personality measure-ments) being significantly different from zero. The highest correlationswere found for self-reports on tender-mindedness with both acceptance ofinequality (r � �.13) and rejecting system change (r � �.15), but zerocorrelations were found with peer reports on tender-mindedness. In fourcases, correlations were consistently significant across self- and peer re-ports of personality. AI was consistently linked to openness to values(self-reports: r � �.08; peer reports: r � �.09) and RC was consistentlylinked to activity (self-reports: r � �.10; peer reports: r � �.10), opennessto values (self-reports: r � �.09; peer reports: r � �.13), and straight-forwardness (self-reports: r � �.08; peer reports: r � �.09). However, inview of these rather small correlations, it seems fair to conclude that thespecific variance in facet scales did not account for a substantial proportionof variance in AI and RC over and above the variance accounted for by thefive broad domains. Therefore, we decided not to run further modelanalyses with these facet residuals.

(A) Model for MZ Twins

M F

T1 T2

S1 S2

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(B) Model for DZ Twins

M F

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d/i d/i

d/i d/i

Figure 2. Extended twin family models for (A) monozygotic (MZ) and(B) dizygotic (DZ) twins. M � mother; F � father; T � twin siblings; S �spouses; A, a � additive genetic factor; D/I, d/i � nonadditive geneticfactor (rD and rI are 1.0 for MZ twin pairs, but rD � .25 and rI � 0.0 forDZ twin pairs); C, c � shared environmental factor; E, e � nonsharedenvironmental factor; �A � genotypic assortative mating; �C � socialhomogamy; �E � spouse-specific effects; m � maternal transmission; f �paternal transmission; s � shared environmental effects specific to twinpairs.

638 KANDLER, BLEIDORN, AND RIEMANN

accounted for by genetic effects on the variance in personalityself-reports, whereas environmental effects on personality vari-ables accounted for less than 10% of the environmental variance inpolitical dimensions (see Table 5). Confidence intervals and crit-ical difference tests suggested that differences between estimatesof the genetic overlap from analyses using self- versus peer reportswere not significant.5

More specific bivariate genetic and environmental correlationsare presented in Table 4. Significant genetic correlations betweenspecific personality traits and political dimensions were replicableacross self- and peer ratings of personality (rG in Table 4). Theenvironmental correlations (rE in Table 4) were generally low andnot consistently significant across self- and peer reports.

Discussion

This study had two major goals: (a) to quantify the sources ofthe variance and spouse covariance in two core aspects of political

orientation using an extended twin family design and (b) to exam-ine the sources of the links between personality traits and politicalorientation. In the following section, we discuss the findings andimplications.

Genetic Sources of Political Orientation

Orientations on the two well-documented dimensions of thepolitical left–right spectrum, that is, attitudes toward inequalityand system change (Jost et al., 2008, Jost et al., 2009), appear tohave a genetic basis, whereas we did not find evidence for envi-ronmental transmission from parents to offspring. That is, theobserved resemblance between the political views of parents andadult offspring did not derive from parental socialization indepen-dent of their genetic contribution. In other words, political beliefsappear to have a genetically based traitlike component. On thebasis of a German sample, this finding is in line with previousstudies on more specific political attitudes in other countries, suchas the United States, Australia, and Canada (Alford et al., 2005;Bell et al., 2009).

Our extended twin family study also confirms the existence ofepistatic interaction effects of genes and genotypic assortativemating in rejecting system change. Both nonadditive genetic ef-fects and genotypic assortative mating increased the genetic vari-ance for this political dimension in the population.

The presence of genetic variance in political dimensions indi-cates that people choose different political positions at least partlyon the basis of their genetic makeup. In addition, the presence ofgenotypic assortative mating as a special form of gene–environment correlation (spouses can be considered a social envi-ronment factor) indicates that genetic factors also contribute to the

5 The 95% confidence intervals of genetic and shared environmentalresidual variance components in political orientations indicated nonsignifi-cance. However, the large confidence intervals were due to lack of powerfor estimating genetic effects in the presence of shared environmentaleffects and vice versa in a classical twin design (see Neale & Maes, 2004).

PE PN PC PO PPOPA

GE GN GC GO GA GPO

EE EN EC EO EA EPO

CPO

Figure 3. For simplicity, the Cholesky decomposition twin model pic-tures only genetic and nonshared environmental factors for one twin.MZ � monozygotic; DZ � dizygotic; P � phenotype; G � genetic factor(rG � 1 for MZ twin pairs and rG � .5 for DZ twin pairs); C � sharedenvironmental factor (rC � 1 for MZ and DZ twin pairs); E � nonsharedenvironmental factor (rE � 0 for MZ and DZ twin pairs); N � Neuroticism;E � Extraversion; O � Openness; A � Agreeableness; C � Conscien-tiousness; PO � political orientation.

Table 2Variance Decomposition of the Extended Twin Family Model (see Figure 2)

Phenotypic component Variance decomposition

Variance a2 � d2 � i2 � c2 � e2

MZ twin covariance a2 � d2 � i2 � c2

DZ twin covariance 1⁄2 � a2 � (1 � �A) � 1⁄4 d2 � c2

Mother–offspring covariance 1⁄2 � a2 � (1 � �A) � c2 � (m � f � �C)Father–offspring covariance 1⁄2 � a2 � (1 � �A) � c2 � (f � m � �C)Spouse covariances a2 � �A � c2 � �C � e2 � �E

MZ twin–cotwin’s spouse covariance a2 � �A � c2 � �C

DZ twin–cotwin’s spouse covariance 1⁄2 � a2 � �A � (1 � �A) � c2 � �C

MZ twins’ spouses covariance a2 � �A2 � c2 � �C

2

DZ twins’ spouses covariance 1⁄2 � a2 � �A2 � (1 � �A) � c2 � �C

2

Mother–offspring’s spouse covariance 1⁄2 � a2 � �A � (1 � �A) � c2 � �C � (m � f � �C)Father–offspring’s spouse covariance 1⁄2 � a2 � �A � (1 � �A) � c2 � �C � (f � m � �C)

Note. Model identification of the models is based on the path coefficient approach (i.e., fixing variances oflatent variables to one). MZ � monozygotic; DZ � dizygotic; a � additive genetic factor; d and i � nonadditivegenetic factors; c � shared environmental factor; e � nonshared environmental factor; �A � genotypicassortative mating; �C � social homogamy; �E � spouse-specific effects; m � weight of maternal transmission;f � weight of paternal transmission. As this model does not allow the disentanglement of different sources ofgenotypic assortative mating, spouse correlations due to nonadditive genetic effects are assumed to be zero.

639SOURCES OF POLITICAL ORIENTATION

likely reciprocal effect in which political positions “choose” peo-ple (Jost et al., 2009). That is, people who choose a specificpolitical position also choose partners with similar attitudes, whoin turn could further intensify or deepen these particular attitudes.

Environmental Sources of Political Orientation

Variance in political attitudes could be attributed to generation-specific environmental influences shared by twins and spouses.That is, beyond genetic sources and genotypic assortative mating,resemblance of twins and spouses in political views appears toresult from generation-specific environmental sources, as sharedenvironmental effects were not significantly linked to parents’beliefs. Shared effects within twin pairs also appear to be highlycorrelated between spouses. Moreover, some of the twins’ non-shared environmental effects were shared by spouses.

These generation-specific common influences may reflect mu-tual interaction or persuasion within sibling pairs and/or withinspousal couples that acts to increase their resemblance. That is, thepolitical beliefs of one sibling or partner may have increased theattractiveness of those political opinions to the other. This suggeststhat twins as well as spouses might both be considered as socialmicrosystems that overlap within a family but differ from othertwin pairs and spousal couples in their political position.

A further possible shared environmental factor for siblings andspouses might be common peers. Friends may be shared by twins,spouses, or both, and they appear to play a crucial role for politicalattitudes (e.g., Dey, 1997). In addition, residential environmentalinfluences mostly shared by spouses (e.g., area of high crime,unemployment, and cultural diversity) could also affect politicalattitudes. Living in an area with a high danger of crime mayincrease the attractiveness of conservative leaders and opinions

(Ullrich & Cohrs, 2007; Willer, 2004), whereas times of highunemployment may increase the advocacy of political change.Even travel experiences shared by spouses, friends, or twins (e.g.,during trips to foreign countries and cultures) can increase theaffinity for progressive and egalitarian ideas (Carney et al., 2008;Leonard, 1964). Therefore, an individual’s political orientationcannot be treated as a purely dispositional characteristic, but it,without a doubt, is also largely affected by the social and economicenvironments (Jost et al., 2003).

More genetically informative studies are warranted to detectcritical environmental factors that may account for variance andchange in political views beyond the genetic makeup. For exam-ple, MZ-twin-difference designs and longitudinal family studies onmeasured intra- and extrafamilial environmental factors may offerinteresting insights into the specific environments likely affectingpolitical attitudes.

Genetic Links Between Personality and PoliticalOrientation

As expected by many authors (Gerber et al., 2010; Jost et al.,2009; Mondak et al., 2010), the phenotypic correlations betweenthe Big Five personality domains (primarily Openness, Agreeable-ness, and Conscientiousness) and political beliefs were due togenetic factors. That is, genetically based personality traits ac-counted for a substantial proportion of the genetic variance in coredimensions of ideology. However, a residual proportion of geneticvariance in political attitudes remained unexplained, contradictingthe strong claims of FFT of personality (McCrae & Costa, 2008).

There are different plausible interpretations for these uniquegenetic effects on political orientations. First, cognitive variablesand outcomes, such as intelligence and labor market attainment,

.04

-.01

.08

-.02

.11

.07

.15*

.08

.12*

.23*

.28*

.24*

.27*

.07

.34*

.28*

.39*

.45*

.31*

.32*

.36*

.53*

Father-offspring's spouse (N = 160)

Mother-offspring's spouse (N = 187)

DZ twins' spouses (N = 70)

MZ twins' spouses (N = 109)

DZ twin-cotwin's spouse (N = 196)

MZ twin-cotwin's spouse (N = 274)

Spouse couples (N = 798)

Father-offspring (N = 268)

Mother-offspring (N = 322)

Dizygo�c twins (N = 166)

Monozygo�c twins (N = 224)

resistance to change acceptance of inequality

Figure 4. This figure illustrates phenotypic correlations of political orientations for different familial relations.For parent–offspring and parent–offspring’s spouse relationships, only one twin with spouse was randomlyassigned. Parent–offspring, parent–offspring’s spouse, and spouse relations also included unmatched twins andfamily. MZ � monozygotic; DZ � dizygotic. � p � .05.

640 KANDLER, BLEIDORN, AND RIEMANN

may also account for the genetic variance in political beliefs. Forinstance, intelligence is a strong predictor of socioeconomic suc-cess (Rowe, Vesterdal, & Rodgers, 1998; Strenze, 2007), which, inturn, may have an effect on a positive attitude toward socialdifferences that defines the success. In addition, a positive attitudetoward preserving the political system in which the success wasreached might be expected (Napier & Jost, 2008). The other wayaround, a recent study found that higher intelligence predictedliberal and antitraditional attitudes, and these effects were partlymediated by educational qualifications (Deary, Batty, & Gale,2008). Perhaps the genetic and environmental links between cog-nitive abilities and political attitudes are nonlinear or in oppositedirections. In line with this idea, academic achievement, which isstrongly linked to cognitive abilities, showed positive geneticallymediated links but negative environmentally mediated links toattitudes toward equality (Olson et al., 2001). In fact, cognitiveabilities can be considered promising candidates in accounting foradditional genetic variance in the two core aspects of politicalorientation, as they show high levels of heritability and initialassortment (Watson et al., 2004) but negligible links to personalitytraits. Moreover, genotypic assortative mating for rejecting systemchange may be linked to genotypic assortative mating for intelli-gence.

Beyond cognitive abilities and Big Five personality traits, fur-ther dispositional characteristics may influence political orienta-tion. Motivational variables, such as major life goals (Bleidorn etal., 2010) and individual interests (Kandler, Bleidorn, Riemann,Angleitner, & Spinath, in press), appear to have a unique geneticbasis that is partly independent of the genetic factors influencing

personality traits. Goals, interests, and values are very plausiblecandidates affecting individuals’ orientation in political life. Forexample, need for structure, need for order, or social dominanceorientation may affect the view of the world as ruthless andthreatening and thus may affect social and economic aspects ofpolitical orientation (Duckitt & Sibley, 2010; Thorisdottir, Jost,Liviatan, & Shrout, 2007).

Finally, one can also think about political orientations as distinctelements of the broader personality system that are systematicallyrelated to personality traits and other dispositional variables butmight still have their own and unique genetic basis. In line withthat idea, Alford and Hibbing (2007) differentiated between per-sonal and political temperaments.

Limitations and Outlook

The current study extends previous research on political atti-tudes and their links to personality traits by using both an extendedtwin family and a multiple-rater design. Yet, several limitationsshould be mentioned that could be addressed by future research.

First, our results indicate that the largest proportion of variancewas due to effects not shared by twins and modestly correlatedbetween spouses, but nonshared environmental effects were con-founded with measurement error. Both scales we used to measurethe two core aspects of ideology showed only moderate reliability.As a consequence, nonshared environmental influences were over-estimated and genetic and shared environmental influences wereunderestimated. Future investigations using more reliable mea-sures of the two domains of political views (Deaux et al., 2006;

Table 3Genetic and Environmental Sources of Political Orientations: The Full and the Best-Fitting Reduced Extended Twin Family Models(see Figure 2) and Parameter Estimates

Parameter or statistic

Political orientation

Acceptance of inequality Rejecting system change

1 2 Best 1 2 Best

Model parameterAdditive genetic effects (a2) .00 .16 .20a .37a .37a .37a

Genetic dominance effects (d2) .08 — — .09 — —Epistatic effects (i2) — .00 — — .10a .10a

Shared environmental effects (c2) .21 .14 .09a .07 .08a .08a

Maternal transmission (m � c2) .09 .04 — .00 .00 —Paternal transmission (f � c2) .06 .01 — .00 .00 —Specific environmental effects (e2) .71a .70a .71a .47a .45a .45a

Phenotypic spouse correlation (�) .17a .17a .18a .45a .46a .45a

Genotypic assortative mating (�A) .29 �.28 — .77a .77a .77a

Social homogamy (�C) .27 .77 .99a .74a .72a .72a

Spouse-specific correlation (�E) .16a .16a .13a .24a .25a .25a

Model fit statistic2 62.00 61.83 63.12 60.57 59.41 59.41df 33 33 37 33 33 35RMSEA .069 .068 .061 .062 .060 .055AIC �4.00 �4.17 �10.88 �5.43 �6.59 �10.59

Note. 1 � full model allowing for allelic interaction within gene loci; 2 � full model allowing for allelic interaction between gene loci; Best � best-fittingmodel with regard to the chi-square difference test and parameter significance; a � additive genetic factor; d and i � nonadditive genetic factors; c � sharedenvironmental factor; e � nonshared environmental factor; �A � genotypic assortative mating; �C � social homogamy; �E � spouse-specific effects; m �weight of maternal transmission; f � weight of paternal transmission; RMSEA � root-mean-square error of approximation; AIC � Akaike informationcriterion. Dashed lines represent parameters that are fixed to zero.aThe value is significant on the basis of a 95% confidence interval.

641SOURCES OF POLITICAL ORIENTATION

Oreg et al., 2008) will probably detect larger effects shared bytwins and spouses as well as stronger links to personality traits.

Second, we focused on the relationship between broad politicalfactors and personality traits. However, some studies demonstratedlinks between Neuroticism and more specific political attitudes,like economic liberalism (e.g., Riemann, Grubich, Hempel, Mergl,& Richter, 1993; Verhulst et al., 2010). Future research mayconcentrate on more specialized political attitudes (e.g., toward thedeath penalty or the equivalence of sexes) and personality facets(e.g., tender-mindedness) to detect more fine-grained genetic aswell as environmental links between personality and politicalbeliefs.

Third, as we only focused on direct effects of personality traits,we ignored possible mediation effects through other individualcharacteristics. For example, Lewis and Bates (2011) found thateffects of Extraversion and Neuroticism on political orientationwere mediated by moral values, such as in-group loyalty andfairness, which are linked to attitudes toward equality versusinequality (Barnea & Schwartz, 1998).

Fourth, our model assumed the absence of population stratifi-cation, gene–environment correlation (beyond genotypic assorta-tive mating), and Gene � Environment interaction. Significantpopulation stratification would be confounded with estimates ofsocial homogamy and, thus, may also explain family resemblance.Estimates of genetic and environmental factors that do not takegene–environment correlation and Gene � Environment interac-tion into account would be inflated.

Fifth, although most previous studies have found that assortativemating for personality is weak and that these weak correlations donot increase with the duration of the partnership (e.g., Buss, 1984;Feng & Baker, 1994; Johnson et al., 2008; Lykken & Tellegen,1993; Watson et al., 2004), a recent population-based study re-ported spouse correlations around .30 for Openness, Agreeable-

ness, and Conscientiousness and that correlations increase overmarriage duration (Rammstedt & Schupp, 2008). As these person-ality traits were found to be primarily linked to political attitudes,it might be interesting for researchers in future longitudinal studiesto examine the sources and the level of assortative mating for thesepersonality traits linked to attitudes with respect to the partner-ships’ duration. It might be that similarity does not increase butthat more similar partners tend to stay together.

Finally, our results from German data are in line with studiesfrom the United States, Australia, and Canada, but findings fromother countries might be different. Although resistance to changewas found to be consistently linked to the right wing across 19different countries, differences were found for acceptance of in-equality between Western and Eastern European countries (Thoris-dottir et al., 2007). Researchers in future studies should take intoaccount such differences between individualistic and collectivisticcountries (Hofstede, 1984) with regard to the sources of politicalorientation.

Conclusion

In sum, our study provides support for specific genetic sourcesof the familial resemblance in two core aspects of political orien-tation both between and within generations (i.e., heritability, ge-notypic assortative mating, and epistatic genetic effects). Thegenetic contributions appear to be substantially but not entirelylinked to personality traits. This finding contradicts the FFT (Mc-Crae & Costa, 2008) and provides support for the position that BigFive personality traits and political attitudes are systematicallyrelated but distinct elements within a broad personality system(Alford & Hibbing, 2007; McAdams & Pals, 2006).

Our study also points to the sources of the environment andinstability in political attitudes from generation to generation (i.e.,

Table 4Phenotypic, Genetic, and Environmental Correlations Between Personality Traits and Political Orientations

Personality variable

Political orientation

Acceptance of inequality Rejecting system change

rP rG rE rP rG rE

ExtraversionSelf-reports �.07� �.05 �.04 .08� .25� �.10Peer reports �.04 �.14 .00 .11� .25� �.00

NeuroticismSelf-reports .01 .00 .01 .05 .08 .04Peer reports �.00 �.08 .03 �.04 �.21� .09

ConscientiousnessSelf-reports �.03 .10 �.09 .21� .31� .14�

Peer reports .06 .10 .02 .11� .21� .04Openness to Experience

Self-reports �.22� �.41� �.16� �.47� �.71� �.23�

Peer reports �.15� �.28� �.10 �.40� �.73� �.19�

AgreeablenessSelf-reports �.33� �.66� �.25� .04 .02 .01Peer reports �.12� �.32� �.05 .06 .13 .02

Note. Phenotypic correlations (rP) were computed between personality self-reports and self-reports on political orientations (n � 872) and betweenpersonality peer reports and self-reports on political orientation (n � 748). Estimates of genetic (rG) and environmental (rE) correlations were based on themultivariate model fitting results (224 monozygotic and 166 dizygotic twin pairs).� p � .05.

642 KANDLER, BLEIDORN, AND RIEMANN

shared environmental effects by twins and spouses but not betweenparents and offspring, epistatic genetic effects). Finally, our studyshows that twins’ and spouses’ resemblance in political attitudesdoes not depend only on shared genetic factors but also on simi-larities in the contextual or even cultural body of thoughts (i.e.,social homogamy) as well as on shared social integration specificfor twins and spouses (i.e., twin-specific and spouse-specificshared environmental effects).

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Table 5Relationships Between Personality Traits and Dimensions of Political Orientation: Best-Fitting Cholesky Twin Models (Figure 3) andParameter Estimates

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NSE variance components of personality domainsExtraversion .50 [.42, .60] .44 [.36, .54]Neuroticism .42 [.34, .52] .62 [.51, .74]Conscientiousness .43 [.35, .52] .66 [.55, .77]Openness .41 [.34, .49] .56 [.46, .66]Agreeableness .50 [.41, .60] .59 [.49, .70]

Political orientations

AI RC AI RC

Variance components common with personalityGenetic .11 [.05, .18] .31 [.22, .41] .04 [.01, .10] .29 [.18, .41]NSE .07 [.03, .13] .04 [.01, .08] .01 [.00, .05] .02 [.00, .05]

Residual variance componentsGenetic .06 [.00, .30] .16 [.00, .33] .13 [.00, .38] .12 [.00, .37]SE .13 [.00, .26] .08 [.00, .26] .13 [.00, .32] .15 [.00, .31]NSE .63 [.53, .73] .41 [.34, .50] .69 [.58, .81] .42 [.35, .52]

Proportions of variance explained by personality (in %)Genetic 61 66 24 71Environmental 9 7 1 5

Model fit statistics2 (df � 133) 120.73 130.24 204.29 201.45RMSEA .000 .006 .051 .050AIC �145.27 �135.76 �61.71 �64.55

Note. AI � acceptance of inequality; RC � rejecting system change; NSE � nonshared environmental component; SE � shared environmentalcomponent; RMSEA � root-mean-square error of approximation; AIC � Akaike information criterion. The 95% confidence intervals appear in brackets.

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Received February 15, 2011Revision received July 15, 2011

Accepted August 22, 2011 �

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