The Social Mobility of Siblings in Comparative Perspective (the SIBMOB project)

This project examines the social class mobility of siblings in more than ten countries with the hope of better understanding why some countries or more socially mobile than others.

Man, woman and child symbol

(See summary in Danish below)

How come some siblings from the same family end up in different social class positions? This is a question that has yet to be fully answered by sociologists.

The EU-funded SIBMOB project will conduct a large-scale comparative study to review the class mobility of siblings. It will provide a novel statistical approach to analysing these family types. Specifically, it will identify how class mobility is generated and why societies differ in their class mobility patterns. It will furnish sociologists with a widely applicable statistical approach to such analysis, including describing how and explaining why they differ both within and between countries. The project will apply its novel approach to data on siblings born during the 20th century in 10 countries.

Read the project description here.










Notice: All publications are Open Access and can be accessed via the links below.


Education and Social Fluidity: A Reweighting Approach - Kristian Bernt Karlsson - Sociological Science, February 2022, open access


Marginal Odds Ratios: What They Are, How to Compute Them, and Why Sociologists Might Want to Use Them - Kristian Bernt Karlson and Ben Jann - Sociological Science, April 2023

Origins of Attainment: Do Brother Correlations in Occupational Status and Income Overlap? - Kristian Bernt Karlson and Jesper Fels Birkelund - European Sociological Review, May 2023, online first

R package em: Generic EM Algorithm – Dongjie Wu - published on R Cran Server, January 2023.

How (Not) to Use Risk Ratios in Sociological Research – Kristian Bernt Karlson and Lincoln Quillian - Socius: Sociological Research for a Dynamic World, July 2023.

Working papers:

Economic Returns to Reproducing Parents’ Field of Study – Jesper Fels Birkelund – preprint at SocArXiv, June 2023.

Family Origins of Life Cycle Attainment: How Brother Correlations Overlap Over the Life Course – Kristian Bernt Karlson – preprint at SocArXiv, June 2023.




The project currently consists of Project PI Associate Professor Kristian Bernt Karlson and research postdocs Jesper Fels Birkelund and Jung In. Previous members of the team are Dongjie Wu (postdoc) and Serena Chow (research assistant). From 2024, Stephan Dochow-Sondershaus will join as postdoc.

The project’s advisory board consists of Florencia Torche (Stanford University), Carina Mood (Stockholm University), Irena Kogan (Mannheim University), Herman van der Werfhorst (Amsterdam University), Richard Breen (Oxford University), and Jacque Hagenaars (Tilburg University).

Two visiting PhD students have joined PI Kristian Bernt Karlson during the project so far: Kim Stienstra (Utrecht University) and Filippo Gioachin (University of Trento).











Name Title Phone E-mail
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Jesper Fels Birkelund Assistant Professor - Tenure Track +4535330624 E-mail
Jung In Postdoc +4535329382 E-mail
Kristian Bernt Karlson Associate Professor - Promotion Programme +4535321588 E-mail

Funded by:

ERC starting grant

SIBMOB is funded by European Research Council (ERC Starting Grant).

Project: Social Class Mobility in Comparative Perspective: Bringing Siblings In (SIBMOB)
Period:  1/2-2021 – 31/1-2026


Kristian Bernt Karlson
Department of Sociology
Telefon: 35 32 15 88


Kristian Bernt Karlson will present preliminary findings from his joint work with Jesper Birkelund on the social class mobility of siblings at Oxford University, Linköping University, and Stockholm University this autumn semester.


PI Kristian Bernt Karlson has been awarded two major career awards:

External researchers (scientific advisory board):

Name Title
Florencia Torche Professor at Stanford University
Irena Kogan Professor at University Mannheim
Carina Mood Professor at Stockholm University
Jacques Hagenaars Professor at Tilburg University
Herman van de Werfhorst Professor at European University Institute
Richard Breen Professor at University of Oxford