County-level map of economic connectedness from "Social capital I: measurement and associations with economic mobility," in Nature. (Figure: Raj Chetty et al)

Friendships in childhood influence incomes in adulthood, and may play an important role in stimulating economic mobility.

In new research published across two papers in Nature, SFI External Professor Matthew Jackson (Stanford), Raj Chetty (Harvard), Theresa Kuchler (NYU), Johannes Stroebel (NYU), and their collaborators analyzed a large sample of Facebook data on more than 70 million U.S. adults ranging from 25 to 44 years old. The researchers measured the strength of the individuals’ social networks and communities, and showed that a particular measure of how connected poorer people are to wealthier people predicts how likely they are to move up the economic ladder over time. Those with lower-income parents, who grew up in counties with a high level of connection between rich and poor, earned 20 percent more, on average, than those with fewer early relationships with wealthy friends.

In the second paper, the researchers delved into how these connections form. They found that institutions such as schools and churches play a major role in facilitating friendships across socioeconomic gaps. 

Read the paper, "Social capital I: measurement and associations with economic mobility" (Nature, 2022) doi:10.1038/s41586-022-04996-4