J. Soc. Phys./
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2605003931
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  • Article

In a Society of Strangers, Kin Is Still Key: Identified Family Relations in Large-Scale Mobile Phone Data

  • Tamás Dávid-Barrett 1,2,3,   
  • Sebastian Diaz 2,4,   
  • Carlos Rodriguez-Sickert 2,   
  • Isabel Behncke 2,   
  • Anna Rotkirch 3,   
  • Loreto Bravo 4,   
  • János Kertész 5,*

Received: 05 Dec 2025 | Revised: 13 May 2026 | Accepted: 14 May 2026 | Published: 08 Jun 2026

Abstract

Mobile call networks have been widely used to investigate communication patterns and the network of interactions of humans at the societal scale. Yet, more detailed analysis is often hindered by the lack of information about the nature of the relationships, even if some metadata about the individuals are available. Using a unique, large mobile phone database with information about individual surnames in a population in which people inherit two surnames: one from their father, and one from their mother, we can differentiate among close kin relationship types. Here, we focus on the difference between the most frequently called alters, depending on whether they are family relationships or not. We find support in the data for two hypotheses: (1) phone calls between family members are more frequent and last longer than phone calls between non-kin; and (2) the phone call pattern between family members show a higher variation depending on the stage of life-course compared to non-family members. We give an interpretation of these findings within the framework of evolutionary anthropology: kinship matters even when demographic processes, such as low fertility, urbanisation and migration, reduce access to family members. Furthermore, our results provide tools for distinguishing between different kinds of kin relationships from mobile call data when information about names is unavailable.

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Dávid-Barrett, T.; Diaz, S.; Rodriguez-Sickert, C.; Behncke, I.; Rotkirch, A.; Bravo, L.; Kertész, J. In a Society of Strangers, Kin Is Still Key: Identified Family Relations in Large-Scale Mobile Phone Data. Journal of Social Physics 2026, 1 (1), 5.
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