How much of your ability to trust others is influenced by your genes? A new study from Australia has revealed that about one-third of the variation in trust among individuals can be traced back to genetics. This research, leveraging data from twins and a comprehensive review of existing studies, sheds light on the complex interplay between our genes and our capacity to trust, a fundamental aspect of human relationships and societal cohesion.
The findings have been published in the Journal of Economic Behavior & Organization.
“Higher levels of trust are associated with a range of social and economic benefits, so understanding the factors that influence our tendency to trust others could be used to improve community wellbeing,” said lead author Nathan Kettlewell of the University of Technology Sydney.
By analyzing data from 1,120 twins, aged 18 to 66, registered with Twins Research Australia, the researchers tapped into a powerful resource for understanding the nature versus nurture debate. This cohort included 401 monozygotic (identical) twins, who share all of their genes, and 159 dizygotic (fraternal) twins, who share roughly half of their genes, with a significant majority being female. This composition allowed the researchers to compare and contrast the levels of trust within twin pairs, offering insights into the genetic versus environmental origins of trust.
“Twin studies are a powerful tool for disentangling genetic and environmental influences on complex traits, as they allow us to compare similarities in trust levels between identical twins, who share 100% of their genes, and fraternal twins, who share on average 50% of their genes,” Kettlewell explained.
Participants underwent a series of measures to assess their trust levels. To gauge political trust, they responded to statements regarding their views on politicians, with their answers providing a direct measure of their trust in the political domain. General trust was evaluated through a single statement from the Global Preferences Survey, where participants rated on a scale how well the statement described them, effectively quantifying their general disposition to trust.
Additionally, the study incorporated a behavioral aspect through a trust game, where participants made decisions on sending money to another player, simulating a trust-based interaction. This game, alongside a strategy method to elicit trustworthiness, allowed the researchers to observe trust in action, beyond self-reported measures.
The research demonstrated that a considerable portion of the variation in trust among individuals can be attributed to genetics, with about 35% of the variation in political trust and 27% of the variation in general trust as measured by survey responses being explained by genetic factors. This suggests that our predisposition to trust others, particularly in political contexts or more generalized settings, is influenced significantly by our genetic makeup.
In contrast, when trust was assessed through behavioral measures, such as the amount of money participants chose to send in a trust game, the genetic influence appeared to be minimal. The study found no significant genetic contribution to behavioral trust and trustworthiness, indicating that these aspects of trust are more heavily shaped by environmental factors and specific situational contexts.
This divergence highlights the complexity of trust as a trait, suggesting that while our general inclination to trust may have a genetic component, the way trust is enacted in specific situations is largely influenced by external factors.
Furthermore, the study delved into the correlations across different measures of trust, uncovering that trust in politicians is only weakly correlated with general trust and not significantly correlated with behavioral measures of trust and trustworthiness. This indicates that trust is a multifaceted construct, with different dimensions being influenced by distinct sets of genetic and environmental factors.
“Trust is a trait that is difficult to define and measure, and it can also change across different domains. For example, someone might show high levels of trust in social relationships but low levels of trust in politics,” explained co-author Agnieszka Tymula, from the University of Sydney.
“Our results don’t imply that people with certain genes are doomed to be high or low in trust. However, when we reflect on our own behavior, and that of people we know, it’s important to recognize that heritability is a component.”
“This can affect how we see ourselves, and how we treat others. For example, recognizing a person’s distrust in politicians is partly due to the lottery of genes, we might come to appreciate why someone who grows up in similar circumstances can have such different beliefs.”
The researchers also explored the unique environmental factors that correlate with trust, finding that concerns about the pandemic and socioeconomic status, among other factors, play a significant role in shaping trust in politicians.
“Our findings suggest that while genetic factors contribute around 33% to the variation in levels of trust observed among individuals, life circumstances such as being older, in better health and married or in a de facto relationship also increase trust,” Kettlewell said.
The genetic correlations between different types of trust revealed modest overlaps, suggesting that while there are common genetic influences on certain aspects of trust, each type of trust also has its unique genetic determinants. This points to the complexity of the genetic architecture underlying trust and the need for further research to unpack these relationships.
Looking ahead, the researchers call for further exploration into the genetic basis of trust, emphasizing the need for larger, more diverse samples and innovative methodologies that can dissect the intricate web of genetics, environment, and trust. This study not only advances our understanding of the genetic components of trust but also opens new avenues for investigating how trust shapes and is shaped by our social environments.
The study, “Heritability across different domains of trust,” was authored by Nathan Kettlewell and Agnieszka Tymula.
