The numbers show that assortative mating really matters. One study indicated that if the marriage patterns of 1960 were imported into 2005, the Gini coefficient for the American economy — the standard measure of income inequality — would fall to 0.34 from 0.43, a considerable drop, given that the scale runs from zero to one. That result is from the economist Jeremy Greenwood, a professor of economics at the University of Pennsylvania, and other co-authors.
A study of Denmark by Gustaf Bruze, a researcher at the Karolinska Institute in Stockholm, showed that about half of the expected financial gain of attending college derived not from better job prospects but from the chance to meet and marry a higher-earning spouse.
There’s not much data on American assortative mating before early in the last century, but a recent paper by Robert D. Mare, a professor of sociology at the University of California, Los Angeles, showed that assortative mating was relatively more common in America’s Gilded Age, fell and reached a much lower level in the 1950s, and afterward started and continued to rise.
Economics itself shows patterns of assortative mating. In 2007, an article in The New York Times cited 13 up-and-coming economists, most of whom have gone on to greater fame. The striking fact is that six of these individuals are married to each other, and that was not the premise of the article. Another person on the list, Justin Wolfers, is a partner with another prominent economist, Betsey Stevenson, with both working at the University of Michigan. (They have two children together but are not legally married; Professor Wolfers is a frequent contributor to The Times.) The children from these kinds of pairings probably have a head start when it comes to pursuing successful careers as research scientists or in other education-intensive endeavors.