Researchers at Edinburgh University's department of psychology report that there is a biological mechanism underpinning the loyalty that a person feels to their social group.
The study investigated whether people are hard-wired to show bias to people of their own religion, ethnicity and race, or whether loyalties depend more on context. This work adds to an extensive body of previous research examining the basis of favouritism and biased behaviour in humans.
The Edinburgh team examined the impact of both genetics and environment on favouritism. To assess the influence of genetics, the scientists asked 1,000 pairs of twins - identical (who share all their genes) and fraternal (who are no more genetically similar to each other than any two siblings) - a series of questions about how important it was for them that people they affiliated with shared their religion, ethnicity or race.
Although the study found that family ties were not as influential as factors like ethnicity and religion, genetically identical twins showed similar favouritism behaviours, while non-identical twins were much more likely to differ in their biases. The researchers also found that people who belonged to a strong religious group were less likely to prioritise ethnic and racial influence when deciding the groups they become involved with, regardless of genetics.
Professor Timothy Bates, who led the study said: 'The success of a coalition reflects the genetic make-up of the group members as well as cultural factors such as and shared goals, beliefs, and traditions. This research could be applied to investigate affiliation in areas such as work, sport and the military'.