https:Power Couples and Marriage Income Inequality//www.joshuakennon.com/sum-small-things-theory-aspirational-class/

Income Inequality Is Caused By Single Parent Households and Assortative Mating Habits Just as Much as Technology

There is considerable academic evidence that one of the major drivers of income inequality in the United States is the difference in family formation, and assortative mating habits, between the upper and lower classes. Stated plainly, the upper class is more likely to get married, stay married, and have children within that marriage, while the lower class is more likely to have children out of wedlock or divorce. The results to net worth and income can be enormous over a lifetime.