Social Homogamy Research Articles

Assortative mating and the dark triad: Evidence from the UK, Fiji, and meta-analytic review

The ‘dark triad’ represents the socially aversive personality traits of Machiavellianism, subclinical narcissism (henceforth, ‘narcissim’), and subclinical psychopathy (henceforth, ‘psychopathy’). There is evidence of assortative mating suggesting romantic partners are more similar than chance for these traits at the start of relationships (initial assortment) and not becoming alike with time (convergence), that people seek out partners to whom they are similar (active assortment), and that partner resemblance is not explained by social stratification processes (social homogamy). As the literature relates primarily to Eastern European and North American populations, we present studies from the UK (N = 104 couples) and Fiji (N = 99 couples). These showed significant positive assortment for each dark triad trait (other than psychopathy in the Fijian sample), and suggest the effects are explained by initial and active assortment and not by convergence or social homogamy. We also submitted the literature to meta-analytic review (Machiavellianism: k = 10, N = 1302; narcissism: k = 14, N = 1645; psychopathy: k = 13, N = 1989) and observed positive within-couple correlations of small (narcissism, psychopathy) to medium (Machiavellianism) effect size for each of the dark triad traits.

Wanted: marriage partner! Partner preferences in newspaper contact adverts in the Netherlands, 1900-1955

ABSTRACT This study examines romantic and instrumental partner preferences in contact adverts from two Dutch newspapers, the Arnhemsche Courant (N = 283) and the Provinciale Drentsche en Asser Courant (N = 231) between 1900 and 1955. With the spread of the newspaper, contact adverts became a new meeting place. By means of short messages, people could make known that they were looking for a partner to get acquainted or even to marry and describe how their desired person should look like. By analysing how advertisers described themselves and their sought-after partners, insights into the motivations behind partner choice were gained. We identified a number of terms in the ads that could indicate romantic partner preferences, such as age homogamy, openness to regional or social heterogamy, and preferences indicating attraction, personality, and appearance. Similarly, instrumental partner preferences could be gathered from phrases expressing social homogamy (marrying into one’s own social class), parental influences, and the importance of wealth or possessions. The results show that romantic and instrumental considerations in partner preferences co-existed, but that their relative occurrence changed over time. Moreover, differential considerations in partner preference existed according to region, urban or rural residence, social class, religion, and gender. For instance, women’s partner preferences were more instrumental than those of men, while urban women were more likely to place contact adverts than rural women. Widows, widowers, and the divorced more often expressed romantic rather than instrumental partner preferences compared to unmarried men and women.

The mechanism of assortative mating for educational attainment: a study of Finnish and Dutch twins and their spouses.

Introduction: Assortative mating refers describes a phenomenon in which individuals with similar phenotypic traits are more likely to mate and reproduce with each other; i.e. assortative mating occurs when individuals choose partners based on their similarity or dissimilarity in certain traits.to patterns of non-random mating of spouses leading to phenotypic resemblance. There are various theories about the its underlying mechanisms, which have different genetic consequences. Methods: We analyzed examined two possible mechanisms underlying assortative mating - phenotypic assortment and social homogamy - for educational attainment in two countries utilizing data of mono- and dizygotic twins and their spouses (1,451 Finnish and 1,616 Dutch twin-spouse pairs). Results: The spousal correlations were 0.51 in Finland and 0.45 in the Netherlands, to which phenotypic assortment contributed 0.35 and 0.30, and social homogamy 0.16 and 0.15, respectively. Conclusion: Both social homogamy and phenotypic assortment are important processes in spouse selection in Finland and the Netherlands. In both countries, phenotypic assortment contributes to a greater degree to the similarity of spouses than social homogamy.

Assortative preferences for personality and online dating apps: Individuals prefer profiles similar to themselves on agreeableness, openness, and extraversion

IntroductionEstablished couples tend to have similar personalities (i.e., assortative mating); however, the mechanism for this effect is unclear. Individuals may initially be attracted to others who are like themselves (i.e., have assortative preferences). Alternatively, couples may become more similar over time. These explanations have been difficult to disentangle. Assortative mating may be less common in online situations as barriers related to social homogamy are removed. The current study experimentally investigates which, if any, of the Big Five personality traits were assortatively preferred in an online environment. MethodsOnline volunteers and paid participants (205 females and 178 males) viewed 100 ostensible dating profiles comprised of random pairings of facial images and personal descriptions, the latter of which were pre-rated for perceived personality. Participants indicated whether they would like to “match” with each profile, mimicking responses made on dating applications, and completed the Big Five Inventory (BFI-44). ResultsParticipants showed assortative preferences for agreeableness, openness, and extraversion, but not for conscientiousness or emotional stability. ConclusionThese results suggest that people exhibit assortative preferences in an online dating app environment. If these online preferences translate to long-term relationships, this could help explain similarities found in established couples identified in previous research.

Genetic assortative mating for schizophrenia and bipolar disorder.

Psychiatric disorders are highly polygenic and show patterns of partner resemblance. Partner resemblance has direct population-level genetic implications if it is caused by assortative mating, but not if it is caused by convergence or social homogamy. Using genetics may help distinguish these different mechanisms. Here, we investigated whether partner resemblance for schizophrenia and bipolar disorder is influenced by assortative mating using polygenic risk scores (PRSs). PRSs from The Danish High-Risk and Resilience Study-VIA 7 were compared between parents in three subsamples: population-based control parent pairs (N=198), parent pairs where at least one parent had schizophrenia (N=193), and parent pairs where at least one parent had bipolar disorder (N=115). The PRS for schizophrenia was predictive of schizophrenia in the full sample and showed a significant correlation between parent pairs (r=0.121, p=0.0440), indicative of assortative mating. The PRS for bipolar disorder was also correlated between parent pairs (r=0.162, p=0.0067), but it was not predictive of bipolar disorder in the full sample, limiting the interpretation. Our study provides genetic evidence for assortative mating for schizophrenia, with important implications for our understanding of the genetics of schizophrenia.

Evidence of assortative mating for theory of mind via facial expressions but not language.

Assortative mating is a phenomenon in which romantic partners typically resemble each other at a level greater than chance. There is converging evidence that social behaviours are subject to assortative mating, though less is known regarding social cognition. Social functioning requires the ability to identify and understand the mental states of others, i.e., theory of mind. The present study recruited a sample of 102 heterosexual couples via an online survey to test if theory of mind as measured using facial expressions (Reading the Mind in the Eyes Test) or language (Stiller-Dunbar Stories Task) is associated with assortative mating. Results provide evidence of assortative mating for theory of mind via facial expressions, though there was no such effect for theory of mind via language. Assortative mating for theory of mind via facial expressions was not moderated by length of relationship nor by partner similarity in age, educational attainment, or religiosity, all variables relevant to social stratification. This suggests assortative mating for theory of mind via facial expressions is better explained by partners being alike at the start of their relationship (initial assortment) rather than becoming similar through sustained social interaction (convergence), and by people seeking out partners that are like themselves (active assortment) rather than simply pairing with those from similar demographic backgrounds (social homogamy).

Do vocational interests matter for the selection of romantic partners? Evidence from variable‐ and couple‐centered approaches

AbstractThe present study links the person–environment fit theory of vocational interests (VI) with the research on the selection of romantic partners. Empirically, we explore the assortment for VI in 215 heterosexual romantic partners. Using both the variable‐centered (VCA) and couple‐centered (CCA) approaches, we test the hypotheses on positive versus negative assortment, initial assortment versus convergence, and active assortment versus social homogamy. A modest to moderate positive assortment was found for Realistic, Investigative, Artistic, and Social interests but not Conventional interests, whereas evidence of couple similarity in Enterprising interests was less consistent. A moderate level of positive assortment was identified in couples when full interest profiles were evaluated. The results indicate an initial and active assortment rather than convergence or social homogamy effects. The analysis also shows that the assortment for interests represents an independent preference that cannot be easily seen as a by‐product of the assortment in the five‐factor personality traits. These findings highlight the importance of VI in the active selection of romantic partners. We discuss implications for future research and practice.

Evidence of partner similarity for autistic traits, systemizing, and theory of mind via facial expressions

It has been hypothesised that romantic partners are more similar than chance in relation to autistic traits. To test this theory, we recruited n = 105 heterosexual couples and examined within-couple correlations for autistic traits [measured using the Autism Spectrum Quotient (AQ)], empathizing [measured using the Empathy Quotient (EQ)], and systemizing [measured using the Systemizing Quotient-Revised (SQ-R)]. For a subsample that attended the lab (n = 58 couples), we also investigated theory of mind via facial expressions using the Reading the Mind in the Eyes Test (RMET) and attention to detail, a component within systemizing, using the Embedded Figures Task (EFT). Variable-centred analyses revealed positive within-couple correlations for all measures except EQ, although these effects were only statistically significant for unmarried couples and not for married/engaged couples. Follow-up analyses indicated that the observed couple similarity effects are likely consistent with people pairing with those more similar than chance (initial assortment) rather than becoming alike over time (convergence), and to seeking out self-resembling partners (active assortment) rather than pairing in this manner via social stratification processes (social homogamy). Additionally, a significant within-couple correlation for autistic traits was observed at the meta-analytic level. However, it should be noted that the meta-analytic effect size estimate was small (r = 0.153) and indicates that only ~ 2% of variance in a person’s score on a phenotypic measure of autistic traits can be predicted by that of their partner.

Social homogamy in Spain at the time of modernisation, 1841–70

ABSTRACT Rather than the exception, social homogamy was the rule in past societies, where ascribed status was a key factor in the matching process. However, frameworks like the modernisation theory predict that as a society modernises, ascribed status loses influence against achieved status. According to this setting, the new economic and social opportunities offered by the industrialisation of an economy enhance the independence of young people from their families in the creation of a new household. This paper makes use of a newly assembled database of around 32,000 marriage records in Spain at the time of its modernisation. Our results show that as the secondary and especially the service sectors increased, the influence of ascribed status decreased and the influence of achieved status increased. The division of the sample in three different social groups shows that this pattern was clearer for the low and middle classes, while modernisation variables do not seem to play any significant role – positive or negative – in the elites, where the marriage markets show a very particular pattern. We believe that the importance of the service sector is related to new job opportunities that appeared for young individuals from the lowest social classes. Although these opportunities could help to improve their independence from their families strengthening their role in the marriage market, it is not that clear that it helped to improve their living conditions.

Gender differences in mate selection criteria among university students in Bangladesh: A study from the social homogamy perspective

Gender differences in mate selection criteria across cultures are common. In various cross-cultural research, these gender differences are explained by different socio-cultural theories. Therefore, the present study was aimed to investigate gender differences in mate selection criteria in Bangladeshi culture and to explain these differences by the social homogamy theory. An unstructured interview method was followed to obtain the aim of the study. A total of 120 unmarried Bangladeshi university students were chosen to participate the study whose age were ranging from 21 to 24 years (M = 22.45, SD = 1.75). The participants were selected by a convenient sampling method from four universities in Bangladesh. They were equally divided in terms of gender and university. A total of twelve mate selection criteria were found in the study, in which each student averagely responded 7.23 criteria. The highest and lowest number of responses were observed in education (n = 108) and residential status (n = 33) criterion, respectively. The top-ranked criterion considered by male and female students was physical attractiveness and education respectively. Gender difference in mate selection preferences was found to be significant in the study. Though, gender difference was significant in age, education, financial status, physical appearance, physical attractiveness, and profession criterion; however, the gender difference was not significant in character, in-law family's education, in-law family's social approval, religion, region, and residential status. Mate selection criteria considered by Bangladeshi students are explained by the social homogamy theory. The study would help Bangladeshi people to be aware of their mate selection in their own Bangladeshi culture.

Marriage choices, social homogamy and modernization in Milan, 1890-1899 and 1950-1959

ABSTRACT Marriage patterns are a key element in the social reproduction of inequalities because, through marriage, socio-economic resources are distributed among individuals and households. Furthermore, the measure by which individuals from different groups marry each other can be considered as an indicator of the grade of openness of a society. From a historical perspective, modernization theory has traditionally predicted a decrease in marital homogamy by social origin. Long-term trends in social homogamy have been investigated in the social history field, and empirical evidence is quite diverse across contexts and periods. We analyzed patterns of social homogamy in Milan using new couple-level data on marriages between the end of the 19th and the first half of the 20th century. Following the modernization framework, we hypothesized that the transition towards an industrial society should be accompanied by an increase in social heterogamy. Results show that, net of changing marginal distributions across social classes, patterns of couple formation remain substantively the same across time. Men appear less mobile than women, who have a higher tendency towards upward marital mobility. As for intermarriage among social classes, boundaries between the top and bottom classes, and barriers between manual and non-manual workers remained strong across time. These results, as previously found in other contexts, do not fully corroborate the modernization theory.

Strengthening the inner circle: the marriage networks of elite families in Joseon Korea

ABSTRACT Socioeconomic homogamy is a prominent process for reproducing the social structure in preindustrial societies including East Asian countries. Although Joseon Korea was a centralized bureaucratic state under a king, the stratification system was unique by its ambiguity such that the previlege of an upper class was not officially confirmed. Since the social status was rather conferred by the reputation of the family, the quality of marriage relation was important for a man to be ranked as a central official. In this paper, we investigate patterns of social homogamy among elite families in the early Joseon Korea through empirical evidence of the relationship between official rank and spousal family background. We created a novel dataset by compiling the marriage network and official rank information of 14,508 individuals from the jokbos (族譜, genealogy) of 15 elite families and conduct an ordinal logit regression analysis to investigate whether spousal family background increases the probability of an individual being promoted in the bureaucracy. We find that the socio-political power of affinal kin has a greater effect on promotions than the descent and meritocratic effects. Particularly, the empirical evidence shows that marrying into a queen consort’s family increased the likelihood of an individual being ranked in a high position, which was beneficial for retaining the political power of him and the family. The study shows that marriage as a means of managing the socio-political inner circle of elite families, shaping the elites’ socio-political inner circle, built on the marriage network around a queen consort’s family to benefit the royal authority and the elite group.

Change in prevalence or preference? Trends in educational homogamy in six European countries in a time of educational expansion

This paper analyzes trends in educational homogamy in six European countries (Sweden, the Czech Republic, Slovakia, Poland, Hungary, and Italy). We use vital statistics on all marriages contracted between 1990 and 2016. Absolute educational homogamy increases in all countries (very moderately in the Czech Republic and Italy), it changes its structure, and the absolute educational hypogamy of women increases. The trends over time and among countries in relative educational homogamy are tested using log-linear and log-multiplicative models. We expand a regression-type layer effect model (the Goodman-Hout model) into a four-way table. The results indicate differing assortative mating by educational categories. Relative homogamy decreases in tertiary education. In lower educational categories, relative homogamy increases. We present the hypothesis that a decrease in relative homogamy in tertiary education is a consequence of the rise of social homogamy. We conceptualize this homogamy balance as a “complementary maintained homogamy.” Because changes in relative educational homogamies are the same in all countries, the cross-country differences remain constant over time. We conceptualize this as a “maintained flux.” The European countries are not in convergence, even though the relative homogamies delineated by educational categories change.

Educational heterogamy during the early phase of the educational expansion: Results from the university town of Tartu, Estonia in the late 19th century

Background: From a historical perspective, the transition from a pre-industrial to a modern society is associated with increasing social status heterogamy. As individuals’ acquired characteristics became more important for partner selection than inherited class status, the importance of status homogamy declined and marrying outside one’s own social group became more frequent. Objective: We investigate educational heterogamy in a university town at the end of the 19th century. We ask whether marriage of unequally educated partners is related to dissimilarity in the partners’ other characteristics. Ethnic background, origin (place of birth), and age difference between the spouses are considered as characteristics that may associate with sorting into educationally heterogamous unions. Methods: The analysis uses data from the 1897 census in Tartu. Using logistic regression modelling, we estimate how age difference, origin heterogamy, and ethnic heterogamy of the spouses associate with educational heterogamy. Results: The results indicate a positive relationship between educational heterogamy and marrying outside one’s own ethnic or origin group, but no effect for spousal age difference. Conclusions: Our study provides new evidence about marriage markets during modernisation, specifically regarding the role of education. We show that educationally heterogamous unions in Tartu were often also more heterogamous in terms of partners’ background characteristics. This suggests that the partner’s education may have motivated intermarriage by ethnicity and origin. Contribution: Previous literature on this period has focused on social homogamy based on occupational information, while research on educational assortative mating mostly exists for the second half of the 20th century and later. We contribute by studying the importance of education in marital selection in the early phase of educational expansion and economic modernisation.

An Extended Twin-Pedigree Study of Different Classes of Voluntary Exercise Behavior

We investigated the familial clustering of different classes of voluntary regular exercise behavior in extended twin-family pedigrees. In contrast to the earlier work based on twin data only, this allowed us to estimate the contributions of shared household effects (C), additive (A), and non-additive (D) genetic effects on voluntary exercise behavior. To test whether shared household effects were inflated by assortative mating we examined the causes of spousal resemblance. For adolescent and adult participants (aged 16 to 65) in the Netherlands Twin Register we constructed 19,543 pedigrees which specified all relations among nuclear family members and larger families in the register (N = 50,690 individuals). Data were available on total weekly MET minutes spent on leisure time exercise, and on total weekly MET minutes spent on exercise activities in team-based, solitary, competitive, non-competitive, externally paced and internally paced exercise. We analyzed the data in the Mendel software package (Lange et al. in Bioinformatics 29(12):1568–1570, 2013) under multiple definitions of household sharing and used data from spouses of twins to test phenotypic assortment, social homogamy, and marital interaction as potential sources of spousal resemblance. Results confirmed the influence of genetic factors on the total volume of weekly exercise behavior throughout the life span. Broad sense heritability ranged from 34 to 41% (19–26% A, 12–21% D), and did not depend on the definition for household sharing. Engaging in team-based, competitive, externally paced activities (e.g., soccer) was ~ 13% more heritable than engaging in non-competitive, solitary activities (e.g., jogging). Having shared a household as siblings explained 4–8% of the variance in adult exercise behavior, whereas sharing a household by spouses yielded higher C estimates (20–24%), as it incorporates spousal resemblance. Spousal resemblance was explained by both social homogamy and marital interaction, with little evidence for phenotypic assortment. We conclude that both the amount of voluntary exercise behavior and the preference for specific classes of exercise activities in adults is explained by additive and non-additive genetic factors and unique environmental influences that include correlated exercise behavior of spouses.

Marriage patterns in a black Utopia: Evidence from early nineteenth-century colonial Sierra Leone

ABSTRACTThe colony of Sierra Leone was characterized by an unusually heterogeneous population made up of immigrants. The diverse population and the dynamics that led to its creation constitute a valuable case study for mating theories. This article examines the determinants of marriage patterns in early nineteenth-century urban Sierra Leone relying on census data. The degree to which marriage-market constraints and preferences influenced marriage patterns is studied. The results of this study suggest that marriage-market constraints contributed to explaining marriage patterns. However, even in a newly founded and multicultural context as that of urban Sierra Leone, social homogamy based on ascribed characteristics was the most prevalent marriage arrangement, in spite of the disruption of kin relations caused by slavery and migration.

Genomic evidence for MHC disassortative mating in humans.

Although pervasive in many animal species, the evidence for major histocompatibility complex (MHC) disassortative mating in humans remains inconsistent across studies. Here, to revisit this issue, we analyse dense genotype data for 883 European and Middle Eastern couples. To distinguish MHC-specific effects from socio-cultural confounders, the pattern of relatedness between spouses in the MHC region is compared to the rest of the genome. Couples from Israel exhibit no significant pattern of relatedness across the MHC region, whereas across the genome, they are more similar than random pairs of individuals, which may reflect social homogamy and/or cousin marriages. On the other hand, couples from The Netherlands and more generally from Northern Europe are significantly more MHC-dissimilar than random pairs of individuals, and this pattern of dissimilarity is extreme when compared with the rest of the genome. Our findings support the hypothesis that the MHC influences mate choice in humans in a context-dependent way: MHC-driven preferences may exist in all populations but, in some populations, social constraints over mate choice may reduce the ability of individuals to rely on such biological cues when choosing their mates.

A historical community approach to social homogamy in the past

ABSTRACT This special issue is devoted to the theme of social homogamy, i.e. the likelihood of an individual marrying someone with the same social status, in past times. This introduction aims to situate each article within a broader framework of what unites this collection: a historical community approach to social homogamy in the past. This approach infuses sociological and historical theories in the historical debates on social homogamy. It does so using state-of-the-art research designs, with comparably coded large-scale datasets both on individuals and their families, as well as on the characteristics of the communities they lived in. Such a multi-level approach is deemed valuable as the communities considerably influenced marriage patterns.

15 - EFFECTS OF ASSORTATIVE MATING ON ESTIMATES OF SNP HERITABILITY

Background Mates are similar to one another across a large number of traits, including liabilities underlying psychiatric disorders. It has long been known that when such phenotypic similarity implies genetic similarity (hereafter, assortative mating), heritability estimates from family and twin studies can be biased. However, the effects of assortative mating, if any, on estimates of heritability from all SNPs in unrelated individuals (SNP-based heritability, h2SNP) have not been investigated to date. Methods We derived mathematically the expected behavior of estimates from Haseman-Elston regression and GREML, and assessed these predictions via simulation. We then assessed in the UK Biobank whether the predicted signatures of assortative mating on h2SNP were observed. Results We show analytically and via simulation that estimates of h2SNP from both GREML and Haseman-Elston regression are typically biased upwards in the presence of assortative mating. However, estimates from Haseman-Elston regression are roughly constant as a function of sample size and number of markers, whereas the ratio of sample size to number of markers strongly affects those from GREML. This difference in estimate behavior allows one to assess in real data whether assortative mating is affecting estimates of h2SNP. When we did this in the UK Biobank for height and IQ, we observed that h2SNP estimates for height that behaved as predicted, but not for h2SNP estimates for IQ. Discussion For many traits, the degree of bias in estimates of h2SNP is expected to be small, but it can be non-trivial for other traits, depending on the degree of assortative mating and the heritability of the traits. For example, based on spousal similarity, we predict that h2SNP estimates of height and IQ are ~25% greater than their true equilibrium values. That we did not observe the predicted pattern of h2SNP estimates for IQ may either suggest that spousal similarity for IQ occurs via mechanisms that do not lead to genetic similarity (e.g., social homogamy) or that the effects of assortative mating on the covariance between causal variants is counter-acted by the forces of natural selection.

Generations, social homogamy and stratification in Finland, 1700–1910

ABSTRACT This study analyses social heterogamy in western and southern Finland during the early stages of industrialisation, from 1700 to 1910. Marriage patterns are examined by comparing the social classes of spouses’ parents, which can be understood as the social origin of the spouse. The rate of heterogamy within the freeholder class was only 19.8%, whereas it was 71.1% in the upper classes, 59.7% in the tenant class and 76.5% in the labour class. In addition, only roughly 20–30% of grooms whose fathers were landowners married brides from lower social classes. Certain individual- and family-level characteristics increased the odds of a heterogamous marriage: remarrying, age difference, being an illegitimate child or a single mother, and the first marriages of those in the labour class. Regarding macro-level variables, we found that higher rates of emigration and poor-relief recipients, along with having a larger Finnish-speaking population, led to higher levels of heterogamy. Other issues increasing the odds of heterogamy included living in the more urbanised or industrialised regions and moving to different regions. This study identified strict marriage patterns, which did not significantly change with respect to heterogamy. Nevertheless, indications exist that industrialisation and urbanisation began eroding the prevailing traditions.