Assortative Mating

Who one chooses as a partner is often thought of as an outcome of romantic love and mutual compatibility. However, on an aggregative level, individuals' decisions about who to marry, cohabit with, and date follow regular patterns. The tendency for individuals to form romantic relationships nonrandomly with respect to a given [Page 124]characteristic or set of characteristics is referred to as assortative mating. Scholars have consistently found a strong tendency for individuals to choose partners who are similar to themselves (homog-amy) on many characteristics including physical attractiveness, social status, educational attainment, IQ, and age. Individuals are also much more likely to marry within than outside their social group (endogamy) as defined by race/ethnicity, religion, and immigrant status. This entry describes why scholars are interested in assortative mating, outlines historical trends in matching patterns, and reviews recent research on differences in matching patterns by relationship type.

Patterns of assortative mating are of interest to social scientists for several reasons. First, marriage patterns are an indicator of a society's openness. Because marriage creates intimate ties between individuals and families, societies that have many marriages across social boundaries are thought to be more open than societies that have few. Second, patterns of assortative mating have consequences for the distribution of resources in societies. Because spouses share resources with one another and potentially one another's families, marriage within socioeconomic groups tends to reinforce inequalities across families, whereas random matching ameliorates inequalities. Third, to the extent that children's traits are learned or inherited from their parents, assortative mating has consequences for the population composition of future generations. Finally, patterns of assortative mating shed light on gender norms and inequalities. Because socioeconomic status often confers power in relationships, marriage patterns in societies in which most men marry “down” (hypergamy) may reflect and reinforce power disparities between husbands and wives.

Historical studies of assortative mating reveal broad shifts in mate selection patterns. In the United States, race/ethnic barriers to marriage have weakened considerably. Although still relatively rare, interracial marriages are now far more common than they were in the 1960s. Interreligious marriages are more common than interracial marriages and have also become increasingly common since the 1960s, but these changes have not been as dramatic as the increase in interracial marriage. By contrast, most studies have found that educational intermarriage has become less common in the United States since the 1960s. In other countries such as Britain, however, educational intermarriage has become more common. Examining the overall resemblance of spouses masks significant changes in gender patterns of assortative mating. For example, since the 1970s, the likelihood that men marry women with less education than themselves has fallen substantially; so much so that in 2000, when one spouse had more education than the other, that spouse was more likely to be the wife than the husband. Thus, the traditional pattern of men marrying down has reversed.

Scholars have proposed several hypotheses to explain observed trends in assortative mating. Modernization theory predicts that as societies industrialize, the basis of success shifts from ascribed characteristics, or those characteristics inherited from one's parents such as race/ethnicity, class background, and to a large extent religion, to achieved characteristics, such as education. Adapting this theory to assortative mating, scholars hypothesize that matching on race/ethnicity, social background, and religion will decline over time whereas matching on education will increase, a hypothesis largely consistent with observed patterns. A related hypothesis is that individuals today have more freedom to intermarry because parents, religious communities, and other third parties have less control over young people's marriage choices as a result of increased geographic mobility and a prolonged interval between nest-leaving and marriage. Other scholars emphasize the potential link between economic inequality and assortative mating. They hypothesize that when economic inequality between groups is large, the “costs” of marrying down will increase, giving individuals a greater incentive to marry homogamously. The difference between the earnings of college graduates and those with less education has increased substantially over the past several decades, a trend that is consistent with the increase in educational homog-amy. Finally, increases in educational assortative mating may also be the result of an increasing symmetry in the preferences of men and women for mates. As women have increased their labor force participation, men may have begun to compete for high-earning, highly educated women, just as women have traditionally competed for high-earning, highly educated men. Increasing symmetry of men's and women's preferences tends to increase educational [Page 125]homogamy as a result of increased competition for highly educated mates.

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