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Assistant Professor of Sociology

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Charles H. Mcllwain University Preceptor

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PRINCETON UNIVERSITY

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 Contact

samtrejo [at] princeton [dot] edu

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(609) 258-4436

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187 Wallace Hall
Princeton, NJ 08544

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Biography

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My name is Sam Trejo—I am a sociologist and demographer interested in how social and biological factors jointly shape human development across the life-course. I specialize in quasi-experimental, computational, and biosocial quantitative methods, and my research typically utilizes large administrative datasets and longitudinal studies containing molecular genetic data.

One branch of my research surrounds polygenic scores, measures meant to summarize a person’s genetic predisposition for a trait (ranging from height to depression to cognitive ability). While polygenic scores are becoming more and more predictive of social, behavioral, and health outcomes, there is much work to be done understanding what exactly is ‘in’ a polygenic score. I study how the social environment mediates, moderates, and confounds associations between genes and outcomes.

Another strand of my research leverages both field and natural experiments to explore the processes that produce educational and health inequality, with an emphasis on the reciprocal relationship between education and health. My work in this area has examined, for example, childhood lead exposure, fatal school shootings, and economic segregation.

I recently wrote a book entitled What We Inherit: How New Technologies and Old Myths Are Shaping Our Genomic Future with my friend and colleague Daphne Martschenko, a bioethicist at Stanford University. Over the past decade, the field of human genetics has rapidly produced a wide range of never-before-seen genomic tools; together, Daphne and I debate and discuss a range of social, ethical, and policy issues raised by this so-called DNA revolution. Though there’s plenty we disagree about, we share a firm belief that—in order to successfully navigate the transition to a society where genetic prediction is increasingly accurate and available—it is vital that we take seriously the impact both of DNA and of pernicious genetic myths. What We Inherit will be published by Princeton University Press in February 2026.

I co-wrote an editorial on the misappropriation of genomics research by white supremacists. A few years ago, I wrote a piece about how my experiences with nerve damage and chronic pain led me to donate a kidney to a stranger. When not puzzling over humans and their behavior, I love biking, playing board games, and spending time with my partner Marissa and our dog Pickle. You can find the R code that I used to create this website here.


Research

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  * Joint lead authorship   § Senior authorship ● PDF   ● FAQ   ● Data/Code   ● Pre-Reg

● Working Papers

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DNA, Self-Reported Ancestry, and Social Scientific Inquiry

Luyin Zhang and Sam Trejo§. SocArXiv.

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Does Standard Adjustment for Genomic Population Structure Capture Direct Genetic Effects?

Ramina Sotoudeh*, Sam Trejo, Arbel Harpak, and Dalton Conley§. bioRxiv.


○ Published & Forthcoming Papers

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2026

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Policing the Boundaries of Blackness: How Black and White Americans Evaluate Racial Self-identifications ●

Marissa Thompson, Sam Trejo, AJ Alvero, and Daphne Martschenko. Forthcoming at American Journal of Sociology.


2025

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Genotypic and Socioeconomic Risks for Depressive Symptoms in Two U.S. Cohorts Spanning Early to Older Adulthood

David A. Sbarra, Sam Trejo, K. Paige Harden, Jeffrey C. Oliver, and Yann C. Klimentidis. Journal of Psychopathology and Clinical Science.


2024

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Using the Phenotype Differences Model to Identify Genetic Effects in Samples of Partially Genotyped Sibling Pairs

Sam Trejo and Klint Kanopka. The Proceedings of the National Academy of Sciences. ●

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Exploring the Fetal Origins Hypothesis Using Genetic Data

Sam Trejo. Social Forces. ●

*WINNER OF THE 2025 BEST PAPER AWARD (ASA BIOLOGY & SOCIETY SECTION)*

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2023

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Beware the Phony Horserace between Genes and Environments

Sam Trejo* and Daphne Martschenko*. Behavioral and Brain Sciences. ●


2022

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Ubiquitous Bias and False Discovery Due to Model Misspecification in Analysis of Statistical Interactions: The Role of the Outcome’s Distribution and Metric Properties

Benjamin W. Domingue, Klint Kanopka, Sam Trejo, Mijke Rhemtulla, and Elliot M. Tucker-Drob. Psychological Methods. ● ●

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Ethical, Anticipatory Genomics Research on Human Behavior Means Celebrating Disagreement

Daphne Martschenko* and Sam Trejo*. Human Genetics and Genomics Advances.


2021

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Modeling Interaction and Dispersion Effects in the Analysis of Gene-Environment Interaction

Benjamin W. Domingue*, Klint Kanopka, Travis T. Mallard, Sam Trejo, and Elliot M. Tucker-Drob§. Behavior Genetics. ● ●

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FoGS Provides a Public FAQ Repository for Social and Behavioral Genomic Discoveries

Daphne Martschenko, Benjamin W. Domingue, Lucas J. Matthews, and Sam Trejo. Nature Genetics. ● ●


2020

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Interactions Between Polygenic Scores and Environments: Methodological and Conceptual Challenges

Benjamin W. Domingue, Sam Trejo, Emma Armstrong-Carter, and Elliot Tucker-Drob. Sociological Science. ●

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Local Exposure to School Shootings and Youth Antidepressant Use

Maya Rossin-Slater*, Molly Schnell*, Hannes Schwandt*, Sam Trejo, and Lindsey Uniat. The Proceedings of the National Academy of Sciences. ●

PRESIDENTIAL ECONOMIC REPORT, WASHINGTON POST, LOS ANGELES TIMES, THE HILL

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The Earliest Origins of Genetic Nurture: The Prenatal Environment Mediates the Association Between Maternal Genetics and Child Development

Emma Armstrong-Carter*, Sam Trejo*, Liam Hill, Kirsty Crossley, Dan Mason, and Benjamin W. Domingue§. Psychological Science. ● ●


2019

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Genetics and Education: Recent Developments in the Context of an Ugly History and an Uncertain Future

Daphne Martschenko*, Sam Trejo*, and Benjamin W. Domingue*. AERA Open.


2018

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Schools as Moderators of Genetic Associations with Life Course Attainments: Evidence from the WLS and Add Heath

Sam Trejo*, Daniel W. Belsky, Jason D. Boardman, Jeremy Freese, Kathleen Mullan Harris, Pamela Herd, Kamil Sicinski, and Benjamin W. Domingue§. Sociological Science.


● Resting Papers

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