Genetic evidence for multiple biological mechanisms underlying in-group favoritism

Psychol Sci. 2010 Nov;21(11):1623-8. doi: 10.1177/0956797610387439. Epub 2010 Oct 25.


In-group favoritism is ubiquitous and associated with intergroup conflict, yet is little understood from a biological perspective. A fundamental question regarding the structure of favoritism is whether it is inflexibly directed toward distinct, "essentialist" categories, such as ethnicity and race, or is deployed in a context-sensitive manner. In this article, we report the first study (to our knowledge) of the genetic and environmental structure of in-group favoritism in the religious, ethnic, and racial domains. We contrasted a model of favoritism based on a single domain-general central affiliation mechanism (CAM) with a model in which each domain was influenced by specific mechanisms. In a series of multivariate analyses, utilizing a large, representative sample of twins, models containing only the CAM or essentialist domains fit the data poorly. The best-fitting model revealed that a biological mechanism facilitates affiliation with arbitrary groups and exists alongside essentialist systems that evolved to process salient cues, such as shared beliefs and ancestry.

Publication types

  • Twin Study

MeSH terms

  • Adult
  • Choice Behavior*
  • Cues
  • Cultural Characteristics
  • Ethnic Groups / psychology
  • Female
  • Humans
  • Male
  • Marriage
  • Middle Aged
  • Models, Psychological
  • Phenotype*
  • Religion and Psychology
  • Social Environment*
  • Social Identification*
  • Social Values
  • Twins, Dizygotic / genetics*
  • Twins, Monozygotic / genetics*