I Was The Third Brother of Five, Doing Whatever I Had To Do To Survive

• Department of Political and Social Sciences

PhD thesis defence by Marco Santacroce

Siblings raised in the same family often grow into remarkably different people. Research shows that more than half of the inequality in income and education in Europe and the United States arises not between families, but within them—among siblings. This highlights the family home as a key environment in shaping individuals, making it a critical channel for the formation of inequality and opportunity as individuals progress from childhood through adolescence to adulthood. This thesis investigates the role of systematic non-shared environmental factors in shaping these within-family disparities. Specifically, it focuses on two such factors: birth order and causal sibling spillovers, both of which affect siblings in patterned ways and contribute to predictable variations in outcomes. While much of sociological stratification research has focused on differences between families, particularly those driven by socioeconomic status, this study shifts attention to the inequalities that emerge among siblings within the same family. By examining how birth order and sibling influences shape individual development and attainment, this study deepens our understanding of how inequality in both outcomes and opportunities can emerge even in seemingly equal environments.

Marco Santacroce is a PhD candidate at the European University Institute. His research focuses on the inequalities that form and develop within the family home. He holds a BA in Economics from the University of Sussex and an MPhil in Development Studies from the University of Cambridge. He has been a visiting researcher at the London School of Economics, Humboldt University, and Stockholm University. Prior to his doctoral studies, he worked in international development with the World Bank, the United Nations, and the International Food Policy Research Institute.