The power of assortative mating

From Assortative Matching at the Top of the Distribution: Evidence from the World's Most Exclusive Marriage Market by Marc Goñi.  From the Abstract.

Using novel data on peerage marriages in Britain, I find that low search costs and marriage-market segregation can generate sorting. Peers courted in the London Season, a matching technology introducing aristocratic bachelors to debutantes. When Queen Victoria went into mourning for her husband, the Season was interrupted (1861–1863), raising search costs and reducing market segregation. I exploit exogenous variation in women's probability to marry during the interruption from their age in 1861. The interruption increased peer-commoner intermarriage by 40 percent and reduced sorting along landed wealth by 30 percent. Eventually, this reduced peers' political power and affected public policy in late nineteenth-century England.

From What happened when the rich stopped intermarrying by Felix Salmon.

Such marriages caused real harm to the daughter's brothers and even fathers. Her brothers were 50% less likely to enter parliament; her family's prestige fell; and she was much less likely to become the kind of terrifying matriarch so familiar to readers of PG Wodehouse.