Childhood Friendships Could Have an Impact on Income, Mobility and Health

The people you were sitting next to in school may matter more than you think. For children from a low-income background, having a friend from a more privileged background may be enough to succeed later in life and thus also have better health. This is shown in a new thesis by PhD student Klara Gurzo from the Department of Public Health Sciences at Stockholm University.

“Income mobility and health are not only individual achievements or outcomes. They are shaped by the social worlds we grow up in,” Gurzo says.

Drawing on decades of Swedish register data and the Stockholm Birth Cohort Multigenerational Study, Gurzo explores a big question: How does income and social mobility shape our health – not just in adulthood, but across generations?

One of the most striking findings in Gurzo’s research centers on childhood friendships. In the second study in her thesis, of more than 10,000 Swedes born in 1953, she examined what happened to children from low-income families who had at least one close friend from a wealthier background. Using data collected in Stockholm classrooms in the 1960s – where children themselves reported their friendships – she followed the participants’ earnings between ages 37 and 48.

Focus on self-reported friendships

The pattern was clear. Children from the lowest income families who had a high-income friend went on to earn significantly more as adults than similar children who did not have such friendships.

“These friendships may provide more than companionship. They can expose children to different ambitions, educational pathways and networks – and even indirect access to resources through a friend’s family,” Gurzo says.

While many previous studies have looked at neighborhoods or schools, Gurzo’s research stands out because it focuses on actual, self-reported friendships. By comparing pupils within the same classroom, she was able to get closer to understanding how peer relationships shape life chances.

The study gained international attention and was highlighted in spring 2025 by the Danish newspaper Weekendavisen.

Income inequality is associated with life expectancy differences
In the first study in her thesis, Gurzo compared two Swedish birth cohorts, 1922–1926 and 1951–1955, in order to assess how income inequalities in life expectancy between ages 50 and 61 changed before and after the expansion of the welfare state.

Growing up in Sweden’s expanding welfare state did not eliminate income differences in life expectancy. For men, gaps between rich and poor widened, and for women, income-related inequalities in survival became clearly visible only in the later generation.

In her third study, Gurzo followed individuals from childhood into adulthood to understand how early economic conditions influence mortality risk. Parental income did matter – but less than one might expect. Much of the link between childhood income and adult mortality was explained by factors such as adolescent cognitive ability, social skills, education and adult income.

In other words, the pathway from childhood disadvantage to early death often runs through education and later-life socioeconomic attainment.

Mobility and mental health

In her fourth study, Gurzo explored how moving up or down the income ladder affects mental health later in life. Looking at men and women between ages 52 and 66, and measuring mental health through prescriptions for psychotropic medication, she found that income mobility was linked to mental health among men – but not women.

The findings suggest that the psychological impact of social mobility may differ by gender, and that social origin and destination both matter.
Inequality should be addressed in early life

All in all, Gurzo’s thesis shows that income-related health inequalities reflect both intergenerational transmission and intragenerational pathways. Social and historical context, as well as individual attributes, shape opportunities for income mobility and health across the life course.

“The findings suggest that efforts to reduce health inequalities should not focus solely on adult socioeconomic conditions. Instead, policies may also need to address early-life environments – including school contexts and peer relations – where social capital, aspirations and opportunities begin to take form,” Gurzo says.

Håkan Soold