Search

A core part of political research is to identify how political preferences are shaped. The nature of these questions is such that robust causal identification is often difficult to achieve, and we are not seldom stuck with observational methods that we know have limited causal validity. The purpose of this paper is to measure the magnitude of bias stemming from both measurable and unmeasurable confounders across three broad domains of individual determinants of political preferences: socio-economic factors, moral values, and psychological constructs. We leverage a unique combination of rich Swedish registry data for a large sample of identical twins, with a comprehensive battery of 34 political preference measures, and build a meta-analytical model comparing our most conservative observational (naive) estimates with discordant twin estimates. This allows us to infer the amount of bias from unobserved genetic and shared environmental factors that remains in the naive models for our predictors, while avoiding precision issues common in family-based designs. The results are sobering: in most cases, substantial bias remains in naive models. A rough heuristic is that about half of the effect size even in conservative observational estimates is composed of confounding.

We use population-wide Swedish data with information on adopted children’s biological and adoptive parents to assess the importance of prebirth factors (measured by biological parents’ voting) and postbirth socialization factors (as captured by adoptive parents’ voting) for generating intergenerational associations in voter turnout. We find that both prebirth and postbirth factors explain the parent-child similarity in turnout behavior. More importantly, we show that the conditions that strengthen the social pathways to intergenerational transmission—such as youth and exposure to consistent parental behavior—at the same time weaken the biological mechanisms and vice versa. Follow-up analyses based on US and UK samples suggest that these results are externally valid. Our findings are important for understanding how political inequality is reproduced across generations.

Estimates from genome-wide association studies (GWAS) of unrelated individuals capture effects of inherited variation (direct effects), demography (population stratification, assortative mating) and relatives (indirect genetic effects). Family-based GWAS designs can control for demographic and indirect genetic effects, but large-scale family datasets have been lacking. We combined data from 178,086 siblings from 19 cohorts to generate population (between-family) and within-sibship (within-family) GWAS estimates for 25 phenotypes. Within-sibship GWAS estimates were smaller than population estimates for height, educational attainment, age at first birth, number of children, cognitive ability, depressive symptoms and smoking. Some differences were observed in downstream SNP heritability, genetic correlations and Mendelian randomization analyses. For example, the within-sibship genetic correlation between educational attainment and body mass index attenuated towards zero. In contrast, analyses of most molecular phenotypes (for example, low-density lipoprotein-cholesterol) were generally consistent. We also found within-sibship evidence of polygenic adaptation on taller height. Here, we illustrate the importance of family-based GWAS data for phenotypes influenced by demographic and indirect genetic effects. Within-sibship genome-wide association analyses using data from 178,076 siblings illustrate differences between population-based and within-sibship GWAS estimates for phenotypes influenced by demographic and indirect genetic effects.

This study leverages population registry data from Sweden to examine whether immigrants who live in areas with a high concentration of ethnic minorities are more or less likely to be nominated for political office. It exploits a refugee placement program in place in Sweden during the late 1980s and early 1990s that restricted refugees' opportunities to freely choose their place of residence. The article presents evidence that immigrants who live in areas with a high ethnic density are less likely to be nominated for political office. The findings have important implications for local integration policies as well as refugee placement policies, as many countries consider local context when resettling refugees.

The absence of a gendered analysis of the effect of marriage on voting is surprising given researchers’ cognizance of the heterogeneous effects of marriage on a range of other social outcomes. In this paper, we shed new light on spousal dependency by studying the gendered effect of marital disruption, in the form of divorce, on voter turnout. First, drawing on Swedish populationwide data, we use the differential timing of divorces in relation to general elections to generate more credible estimates of the causal effect of divorce on turnout. Second, although we find that both sexes are adversely affected by divorce, we show that the effect is much more pronounced for men. Specifically, the long-term effect is almost twice as large for men. Finally, we use these data to show that the gendered effect of divorce is mainly driven by asymmetrical spousal mobilization due to higher levels of turnout among women.

What is the effect of residing in ethnic enclaves on immigrants’ future political participation? We study a comprehensive refugee placement reform that was implemented in Sweden in the mid-1980s in combination with unique individual-level turnout data to study the causal effect of being settled in neighborhoods with a high residential concentration of coethnics on immigrants’ future probability of voting. We find little evidence that ethnic concentration per se affects voter turnout. On average, newly arrived immigrants were equally likely to vote whether they were placed in a neighborhood with many or few coethnics. Further analyses, however, indicate that the effect of ethnic concentration depends on the degree of political integration among previously settled coethnics; ethnic concentration increases turnout among the newly immigrated when they are placed with already politically integrated coethnics. These results underscore the conditions under which the political socialization of immigrant newcomers is enhanced in ethnic enclaves.

Previous studies have stressed the role of a child's family environment for future political participation. This field of research has, however, overlooked that children within the same family have different experiences depending on their birth order. First-borns spend their first years of life without having to compete over their parents' attention and resources, while their younger siblings are born into potential rivalry. We examine differences in turnout depending on birth order, using unique population-wide individual level register data from Sweden and Norway that enables precise within-family estimates. We consistently find that higher birth order entails lower turnout, and that the turnout differential with respect to birth order is stronger when turnout is lower. The link between birth order and turnout holds when we use data from four other, non-Nordic countries. This birth order effect appears to be partly mediated by socio-economic position and attitudinal predispositions.

It is a well-established fact, from decades of research on political socialization, that the children of politically active parents are more likely to become politically active themselves. This poses a challenge for democracy, as it means that inequalities in political influence are reproduced across generations. The present study argues that this problem may be more severe than has hitherto been acknowledged. The reason for this is that previous research on the topic has focused almost exclusively on political transmission between parents and their children, whereas the role played by more distant forebears, such as grandparents, has been largely neglected. In this study, we use Swedish register data to analyze multigenerational associations in electoral participation. The empirical results clearly indicate that the traditional two-generation approach to the study of political transmission tends to underestimate intergenerational persistence in voting behavior and that this excess persistence has both genetic and social roots.

Twin and adoption studies have shown that individual differences in political participation can be explained, in part, by genetic variation. However, these research designs cannot identify which genes are related to voting or the pathways through which they exert influence, and their conclusions rely on possibly restrictive assumptions. In this study, we use three different US samples and a Swedish sample to test whether genes that have been identified as associated with educational attainment, one of the strongest correlates of political participation, predict self-reported and validated voter turnout. We find that a polygenic score capturing individuals' genetic propensity to acquire education is significantly related to turnout. The strongest associations we observe are in second-ordermidterm elections in the United States and European Parliament elections in Sweden, which tend to be viewed as less important by voters, parties, and the media and thus present a more information-poor electoral environment for citizens to navigate. A within-family analysis suggests that individuals' education-linked genes directly affect their voting behavior, but, for second-order elections, it also reveals evidence of genetic nurture. Finally, a mediation analysis suggests that educational attainment and cognitive ability combine to account for between 41% and 63% of the relationship between the genetic propensity to acquire education and voter turnout.

Benjamin et al. construct polygenic indexes (DNA-based predictors) for 47 phenotypes and make them available to researchers in 11 datasets. They also present a theoretical framework and estimator to help interpret analyses using polygenic indexes. Polygenic indexes (PGIs) are DNA-based predictors. Their value for research in many scientific disciplines is growing rapidly. As a resource for researchers, we used a consistent methodology to construct PGIs for 47 phenotypes in 11 datasets. To maximize the PGIs' prediction accuracies, we constructed them using genome-wide association studies-some not previously published-from multiple data sources, including 23andMe and UK Biobank. We present a theoretical framework to help interpret analyses involving PGIs. A key insight is that a PGI can be understood as an unbiased but noisy measure of a latent variable we call the 'additive SNP factor'. Regressions in which the true regressor is this factor but the PGI is used as its proxy therefore suffer from errors-in-variables bias. We derive an estimator that corrects for the bias, illustrate the correction, and make a Python tool for implementing it publicly available.

If two elections are held at the same day, why do some people choose to vote in one but to abstain in another? We argue that selective abstention is driven by the same factors that determine voter turnout. Our empirical analysis focuses on Sweden where the (aggregate) turnout gap between local and national elections has been about 2-3%. Rich administrative register data reveal that people from higher socio-economic backgrounds, immigrants, women, older individuals, and people who have been less geographically mobile are less likely to selectively abstain.

While recent research finds strong evidence that birth order affects outcomes such as education, IQ scores, earnings, and health, the evidence for effects on political outcomes is more limited. Using population-wide data from Sweden, our within-family estimates show that firstborns are significantly more likely to run for and be elected to political office. In addition, for the males in our sample we test whether a number of potential mechanisms account for the relationship between birth order and political participation. Disconfirming our expectations, the birth order effects are only marginally smaller when controlling for occupational economic status, cognitive ability, and leadership skills. Our results suggest that big brother, or for that matter big sister, not only sees us; to a certain extent he or she also rules us.

Many studies have shown that political efficacy, interest in politics, and political knowledge are strongly related to political participation. In most analyses, these variables are described as having a causal effect on participation. In this paper, we examine the extent to which the relationship between political attitudes and participation is confounded by familial factors. By using the discordant twin design, which relates within-pair differences in political attitudes to within-pair differences in political participation, we are able to examine the relationship net of confounding factors rooted in genes and the early rearing environment. Using four samples of monozygotic twins from the United States, Sweden, Germany, and Denmark, we find that the relationship between political attitudes and political participation is confounded to a large extent. This study makes an important contribution to the literature on political attitudes and political participation given the longstanding idea that attitudes cause political participation. Our findings also have practical implications for those interested in elevating levels of political participation. In addition, they have important implications for how scholars theorize about, model, and examine political participation in the future.

Previous studies have stressed the role of a child's family environment for future political participation. This field of research has, however, overlooked that children within the same family have different experiences depending on their birth order. First-borns spend their first years of life without having to compete over their parents' attention and resources, while their younger siblings are born into potential rivalry. We examine differences in turnout depending on birth order, using unique population-wide individual level register data from Sweden and Norway that enables precise within-family estimates. We consistently find that higher birth order entails lower turnout, and that the turnout differential with respect to birth order is stronger when turnout is lower. The link between birth order and turnout holds when we use data from four other, non-Nordic countries. This birth order effect appears to be partly mediated by socio-economic position and attitudinal predispositions.

Student mock elections are conducted in schools around the world in an effort to increase political interest and efficacy among students. There is, however, a lack of research on whether mock elections in schools enhance voter turnout in real elections. In this article, we examine whether the propensity to vote in Swedish elections is higher among young people who have previously experienced a student mock election. The analysis is based on unique administrative population-wide data on turnout in the Swedish 2010 parliamentary election and the 2009 European Parliament election. Our results show that having experienced a mock election as a student does not increase the likelihood of voting in subsequent real elections. This result holds when we study both short- and long-term effects, and when we divide our sample into different parts depending on their socio-economic status and study each part separately.

We examine how one's adult political participation is affected by having social ties to a politician during adolescence. Specifically, we estimate the long-term effect of having had a classmate during upper secondary school whose parent was running for office on future voter turnout and the likelihood of running for and winning political office. We use unique Swedish population-wide administrative data and find that students in school classes with a larger number of politically active parents are more politically active as adults, both in terms of voting and political candidacy. Our results suggest that the effect of vertical social ties is predominantly mediated by indirect links between the politician and the student via the children of politicians. Moreover, we show that the strength of these mobilizing effects depends on the individual's basic predisposition to engage in different types of political activities.

Humans vary substantially in their willingness to take risks. In a combined sample of over 1 million individuals, we conducted genome-wide association studies (GWAS) of general risk tolerance, adventurousness, and risky behaviors in the driving, drinking, smoking, and sexual domains. Across all GWAS, we identified hundreds of associated loci, including 99 loci associated with general risk tolerance. We report evidence of substantial shared genetic influences across risk tolerance and the risky behaviors: 46 of the 99 general risk tolerance loci contain a lead SNP for at least one of our other GWAS, and general risk tolerance is genetically correlated (|r^g| ~ 0.25 to 0.50) with a range of risky behaviors. Bioinformatics analyses imply that genes near SNPs associated with general risk tolerance are highly expressed in brain tissues and point to a role for glutamatergic and GABAergic neurotransmission. We found no evidence of enrichment for genes previously hypothesized to relate to risk tolerance., For complete list of authors see http://dx.doi.org/10.1038/s41588-018-0309-3

It is well documented that voter turnout is lower among persons who grow up in families from a low socioeconomic status compared with persons from high-status families. This paper examines whether reforms in education can help reduce this gap. We establish causality by exploiting a pilot scheme preceding a large reform of Swedish upper secondary education in the early 1990s, which gave rise to exogenous variation in educational attainment between individuals living in different municipalities or born in different years. Similar to recent studies employing credible identification strategies, we fail to find a statistically significant average effect of education on political participation. We move past previous studies, however, and show that the reform nevertheless contributed to narrowing the voting gap between individuals of different social backgrounds by raising turnout among those from low socioeconomic status households. The results thus square well with other recent studies arguing that education is particularly important for uplifting politically marginalized groups.

What motivates citizens to run for office? Recent work has shown that early life parental socialization is strongly associated with a desire to run for office. However, parents not only shape their children's political environment, they also pass along their genes to those same children. A growing area of research has shown that individual differences in a wide range of political behaviors and attitudes are linked to genetic differences. As a result, genetic factors may confound the observed political similarities among parents and their children. This study analyzes Swedish register data containing information on all nominated and elected candidates in the ten parliamentary, county council, and municipal elections from 1982 to 2014 for a large sample of adoptees and their adoptive and biological parents. By studying the similarity in political ambition within both adoptive and biological families, our research design allows us to disentangle so-called pre-birth factors, such as genes and pre-natal environment, and post-birth factors like parental socialization. We find that the likelihood of standing as a political candidate is twice as high if one's parent has been a candidate. We also find that the effects of pre-birth and post-birth factors are approximately equal in size. In addition, we test a number of potential pre- and post-birth transmission mechanisms. First, disconfirming our expectations, the pre-birth effects do not seem to be mediated by cognitive ability or leadership skills. Second, consistent with a role modeling mechanism, we find evidence of a strong transmission in candidacy status between rearing mothers and their daughters.

Here we conducted a large-scale genetic association analysis of educational attainment in a sample of approximately 1.1 million individuals and identify 1,271 independent genome-wide-significant SNPs. For the SNPs taken together, we found evidence of heterogeneous effects across environments. The SNPs implicate genes involved in brain-development processes and neuron-to-neuron communication. In a separate analysis of the X chromosome, we identify 10 independent genome-wide-significant SNPs and estimate a SNP heritability of around 0.3% in both men and women, consistent with partial dosage compensation. A joint (multi-phenotype) analysis of educational attainment and three related cognitive phenotypes generates polygenic scores that explain 11-13% of the variance in educational attainment and 7-10% of the variance in cognitive performance. This prediction accuracy substantially increases the utility of polygenic scores as tools in research.

We introduce multi-trait analysis of GWAS (MTAG), a method for joint analysis of summary statistics from genome-wide association studies (GWAS) of different traits, possibly from overlapping samples. We apply MTAG to summary statistics for depressive symptoms (N-eff = 354,862), neuroticism (N = 168,105), and subjective well-being (N = 388,538). As compared to the 32, 9, and 13 genome-wide significant loci identified in the single-trait GWAS (most of which are themselves novel), MTAG increases the number of associated loci to 64, 37, and 49, respectively. Moreover, association statistics from MTAG yield more informative bioinformatics analyses and increase the variance explained by polygenic scores by approximately 25%, matching theoretical expectations.

Over the years, many suggestions have been made on how to reduce the importance of family background in political recruitment. In this study, we examine the effectiveness of one such proposal: the expansion of mass education. We utilize a difference-in-difference strategy to analyze how a large school reform launched in Sweden in the 1950s, which lengthened schooling and postponed tracking, affected the likelihood of individuals with different family backgrounds to run for public office. The data come from public registers and pertain to the entire Swedish population born between 1943 and 1955. The empirical analysis provides strong support for the view that improved educational opportunities for individuals from disadvantaged backgrounds can be an effective means to reduce the social bias of elected assemblies.

One of the clearest results in previous studies on social trust is the robust positive relationship with educational attainment. The most common interpretation is that education has a causal effect on social trust. The theoretical argument and empirical results in this article suggest a different interpretation. We argue that common preadult factors such as cognitive abilities and personality traits rooted in genes and early-life family environment may confound the relationship between educational attainment and social trust. We provide new evidence on this question by utilizing the quasi-experiment of twinning. By looking at the relationship between education and social trust within monozygotic (MZ) twin pairs, we are able to avoid potential confounders rooted in genetic factors and common environmental influences because the monozygotic twins share both. The results suggest that when controlling for such familial factors the estimated effects of education on social trust are close to zero and far from reaching statistical significance. Further analyses show that the relationship between education and social trust largely is driven by common genetic factors.

Inspired by recent studies on personality and political attitudes and behavior we use the Big Five approach to assess the influence of a comprehensive set of personality traits on political tolerance. Our study is based on surveys in Bhopal in India and Lahore in Pakistan. We find that all Big Five traits – openness, conscientiousness, extraversion, agreeableness, and neuroticism – are significantly related to individuals’ willingness to grant political rights to groups they dislike in one or both countries. As one of only a few studies examining the relationship between the Big Five traits and political attitudes and behavior outside a Western context these findings demonstrate the importance of also paying attention to personality traits when studying contexts where situational factors such as political violence, poverty, and severe inequalities might be expected to be the main influence on individuals’ behavioral choices., Toledo

This paper employs a between-grades regression discontinuity design to estimate the causal effect of education on political knowledge, intention to participate and democratic values. Using data on attitudes and knowledge among about 30,000 students from Greece, Norway, Slovenia and Sweden, we employ a fuzzy regression discontinuity design in which we exploit the exogenous variation related to school entry age. By comparing students who are born around the New Year cut-off point we estimate the causal effect of the ninth year of schooling. Results show that an additional year of schooling has no detectable effect on political knowledge, democratic values or political participation.

In this study we provide new evidence on the much-discussed effect of education on political participation by utilizing the quasi-experiment of twinning. By looking at the relationship between education and participation within monozygotic (MZ) twin pairs we are able to circumvent traditional sources of confounding of the relationship rooted in genes and early life family environment because MZ twins share both. The results of within-twin pair analyses based on surveys from the United States, Denmark and Sweden show that while the relationship between education and political participation is highly confounded by genes and/or familial environment in all three countries, a positive impact remains of years of education in the US and of high school completion in Denmark. No effect is found in Sweden. Robustness checks suggest that the observed effect is not confounded by within-twin pair differences in prenatal environment nor differential treatment during childhood, and, if anything, that it most likely constitutes a lower bound estimate.

Educational attainment is strongly influenced by social and other environmental factors, but genetic factors are estimated to account for at least 20% of the variation across individuals(1). Here we report the results of a genome-wide association study (GWAS) for educational attainment that extends our earlier discovery sample(1,2) of 101,069 individuals to 293,723 individuals, and a replication study in an independent sample of 111,349 individuals from the UK Biobank. We identify 74 genome-wide significant loci associated with the number of years of schooling completed. Single-nucleotide polymorphisms associated with educational attainment are disproportionately found in genomic regions regulating gene expression in the fetal brain. Candidate genes are preferentially expressed in neural tissue, especially during the prenatal period, and enriched for biological pathways involved in neural development. Our findings demonstrate that, even for a behavioural phenotype that is mostly environmentally determined, a well-powered GWAS identifies replicable associated genetic variants that suggest biologically relevant pathways. Because educational attainment is measured in large numbers of individuals, it will continue to be useful as a proxy phenotype in efforts to characterize the genetic influences of related phenotypes, including cognition and neuropsychiatric diseases.

Widespread and persistent political underrepresentation of immigrant-origin minorities poses deep challenges to democratic practice and norms. What accounts for this underrepresentation? Two types of competing explanations are prevalent in the literature: accounts that base minority underrepresentation on individual-level resources and accounts that emphasize political opportunity structures. However, due to the lack of data suitable for testing these explanations, existing research has not been able to adjudicate between these theories. Using registry-based microdata covering the entire Swedish adult population between 1991 and 2010 our study is the first to empirically evaluate these alternative explanations. We examine election outcomes to municipal councils over the course of six elections and find that variation in individual-level resources cannot explain immigrants' underrepresentation. Further, when comparing immigrants and natives who face comparable political opportunity structures a large representation gap remains. Instead, we argue that discrimination by party gatekeepers plays a more significant role in perpetuating the underrepresentation of immigrants than do individual resources or structural variables.

Almost 40 years ago, evidence from large studies of adult twins and their relatives suggested that between 30 and 60 % of the variance in social and political attitudes could be explained by genetic influences. However, these findings have not been widely accepted or incorporated into the dominant paradigms that explain the etiology of political ideology. This has been attributed in part to measurement and sample limitations, as well the relative absence of molecular genetic studies. Here we present results from original analyses of a combined sample of over 12,000 twins pairs, ascertained from nine different studies conducted in five democracies, sampled over the course of four decades. We provide evidence that genetic factors play a role in the formation of political ideology, regardless of how ideology is measured, the era, or the population sampled. The only exception is a question that explicitly uses the phrase “Left–Right”. We then present results from one of the first genome-wide association studies on political ideology using data from three samples: a 1990 Australian sample involving 6,894 individuals from 3,516 families; a 2008 Australian sample of 1,160 related individuals from 635 families and a 2010 Swedish sample involving 3,334 individuals from 2,607 families. No polymorphisms reached genome-wide significance in the meta-analysis. The combined evidence suggests that political ideology constitutes a fundamental aspect of one’s genetically informed psychological disposition, but as Fisher proposed long ago, genetic influences on complex traits will be composed of thousands of markers of very small effects and it will require extremely large samples to have enough power in order to identify specific polymorphisms related to complex social traits., Nature, nurture, and political orientations

This article analyzes a rich Swedish data set with information on the electoral turnout of a largesample of adoptees, their siblings, their adoptive parents, and their biological parents. We use asimple regression framework to decompose the parent-child resemblance in voting into pre-birthfactors, measured by biological parents’ voting, and post-birth factors, measured by adoptive parents’voting. Adoptees are more likely to vote if their biological parents were voters and if they were assignedto families in which the adoptive parents vote. We find evidence of interactions between the pre- andpost-birth factors: the effect of the post-birth environment on turnout is greater amongst adoptees whosebiological mothers are nonvoters. We also show that the relationships between parental characteristics,such as education, and child turnout, persist even in the absence of a genetic link between parent andchild. The regression-based framework we utilize provides a basis for the integration of behavior-geneticresearch into mainstream political science., Nature, nurture and political attitudes and behavior

Recent research demonstrates that a wide range of political attitudes, beliefs, and behaviors canbe explained in part by genetic variation. However, these studies have not yet identied themechanisms that generate such a relationship. Some scholars have speculated that psychologicaltraits mediate the relationship between genes and political participation, but so far there havebeen no empirical tests. Here we focus on the role of three psychological traits that are believed toinuence political participation: cognitive ability, personal control, and extraversion. Utilizinga unique sample of more than 2,000 Swedish twin pairs, we show that a common genetic factorcan explain most of the relationship between these psychological traits and acts of politicalparticipation as well as predispositions related to participation. While our analysis is not adenitive test, our results suggest an upper bound for a proposed mediation relationship betweengenes, psychological traits, and political participation., Nature, nurture, and political attitudes and behavior

A recent genome-wide-association study of educational attainment identified three single-nucleotide polymorphisms (SNPs) whose associations, despite their small effect sizes (each R-2 approximate to 0.02%), reached genome-wide significance (p < 5 x 10(-8)) in a large discovery sample and were replicated in an independent sample (p < .05). The study also reported associations between educational attainment and indices of SNPs called polygenic scores. In three studies, we evaluated the robustness of these findings. Study 1 showed that the associations with all three SNPs were replicated in another large (N = 34,428) independent sample. We also found that the scores remained predictive (R-2 approximate to 2%) in regressions with stringent controls for stratification (Study 2) and in new within-family analyses (Study 3). Our results show that large and therefore well-powered genome-wide-association studies can identify replicable genetic associations with behavioral traits. The small effect sizes of individual SNPs are likely to be a major contributing factor explaining the striking contrast between our results and the disappointing replication record of most candidate-gene studies.

Nature, nurture, and political orientations

This study of political tolerance in India reveals a positive correlation between such tolerance and membership in political parties and unions, and living in urban areas. Surprisingly, the study finds no difference in the levels of political tolerance between RIP and Congress (I) supporters, and no connection with education levels.

Recent studies have shown that trusting attitudes and behavior are biologically influenced. Focusing on the classic trust game, it has been demonstrated that oxytocin increases trust and that humans are endowed with genetic variation that influences their behavior in the game. Moreover, several studies have shown that a large share of the variation in survey responses to trust items is accounted for by an additive genetic component. Against this backdrop, this article makes two important contributions. First, utilizing a unique sample of more than 2,000 complete Swedish twin pairs, we provide further evidence of the heritability of social trust. Our estimates of the additive genetic component in social trust were consistent across the sexes - .33 for males and .39 for females - and are similar to the results reported in earlier studies. Secondly, we show that social trust is phenotypically related to three psychological traits - extraversion, personal control, and intelligence - and that genetic factors account for most of these correlations. Jointly, these psychological factors share around 30% of the genetic influence on social trust both for males and females. Future studies should further explore the possible causal pathways between genes and trust using panel data on both psychological traits and social trust.

Diversity has powerful advantages, but may also generate internal tensions and low interpersonal trust. Despite extensive attention to these questions, the relationship between diversity and trust is often misunderstood and findings methodologically flawed. In this article, we specify two different mechanisms and adherent hypotheses. An individual might base her decision to trust on her perceived social similarity in relation to others in the community, that is, a similarity hypothesis. However, in a homogenous context, she might expect trustworthy behavior irrespective of her own social position due to signals of low degrees of social conflict and dense social networks, that is, a homogeneity hypothesis. Prior research has pinpointed only one of these mechanisms. The homogeneity hypothesis has not been explicated, and when the intention has been to test the similarity hypothesis, the homogeneity hypothesis has unintentionally been tested instead. The results are straightforward. While the homogeneity hypothesis is strongly supported, the findings speak against the similarity hypothesis.

TOLEDO

TOLEDO

TOLEDO

The purpose of this study is to re-examine the support for the 'oil hinders democracy' hypothesis. Following Michael Ross' seminal article 'Does oil hinder democracy?' (2001), the hypothesis has been supported by a number of cross-national empirical tests. We will proceed along two routes, one conceptual and one temporal/contextual. Using time-series cross-section data from 132 countries between 1977-2006 we find that Ross' theory does not stand the test of time, and that a broader conceptual take on the notion of democracy has left the theory more inconclusive than in previous studies. The jury appears to be out concerning the generality of the 'oil hinders democracy' hypothesis.

Citizen support for political institutions is a key component of any representative democracy. Two main approaches to explain political support can be found in the relevant literature: (i) Socio-cultural theories assume that political support is politically exogenous and emphasize factors such as social trust when explaining political support. (ii) Proponents of performance-based explanations, in contrast, see political support as primarily driven by politically endogenous factors, such as people's experiences of political authorities and institutions and evaluations of their performance. In this article I argue that the earlier research has missed an important source of interaction between these two sets of explanatory factors. More precisely, I hold that generalized or social trust plays a central but hitherto misunderstood role in explaining political support. The main hypothesis states that the effects on political support of performance-related factors are greater among low trusters compared to high trusters. I test this interaction hypothesis in a multilevel model, using cross-national survey data from 23 European countries. The results strongly confirm the stated hypothesis.

Tolerance and Democracy (TOLEDO)