CLAIRE CAIN MILLER and QUOCTRUNG BUI:

Researchers say the rise in assortative mating is closely linked to income inequality. The two have increased in tandem, Dr. Schwartz, the sociologist from the University of Wisconsin, said: “People who are married tend to be more advantaged, and on top of that, more advantaged people are marrying people like themselves, so those people tend to be doubly advantaged.”

The effects could become more pronounced in future generations. Studies tell us that parents’ income and education have an enormous effect on children’s opportunities and achievements — and children today are more likely to grow up in homes in which parents are more similar than different.