Sebastián is a sixth-year PhD candidate in the Department of Sociology. His research spans political sociology, organizational sociology, and the sociology of development. His dissertation explores how state agencies in Colombia developed pockets of organizational effectiveness while implementing peace-related policies, despite the country's ongoing conflict and successive peace processes since the 1980s. His research also examines the history of violence as a topic of social scientific study in Latin America, the comparative historical sociology of the state, and the response of U.S.-based nonprofits to changes in domestic legislation.

Sebastián graduated summa cum laude from New York University Abu Dhabi (NYUAD) in 2017, where he studied Social Research and Public Policy with a concentration in Economics. At Princeton, he was a Lassen Fellow in the Program in Latin American Studies during the 2019-2020 academic year, and a Laurance S. Rockefeller Graduate Prize Fellow in the University Center for Human Values during the 2024-2025 academic year.