Twins show trust is in our genes, but distrust isn’t

(Credit: Getty Images)

Trust may depend, at least in part, on genes. But, a new study suggests people may not inherit distrust in the same way.

The study explores distrust as a separate and distinct quality from trust.

“This research supports the idea that distrust is not merely the opposite of trust,” says Martin Reimann, assistant professor of marketing at the University of Arizona and lead author of the study in the Proceedings of the National Academy of Sciences.

“Both trust and distrust are strongly influenced by the individual’s unique environment, but what’s interesting is that trust seems to be significantly influenced by genetics, while distrust is not. Distrust appears to be primarily socialized.”

For the study, researchers studied sets of adult identical twins, who have identical genetic relatedness, and adult fraternal (or non-identical) twins, who have different genetic relatedness.

Based on the core principles of behavioral genetics, if genetics explain variations in distrust and trust behaviors, then identical twins should behave more similarly to each other than fraternal twins, since the genes of identical twins are shared, while the genes of fraternal twins are only imperfectly correlated, Reimann says.

Studying the two different types of twins allowed researchers to estimate the relative influence of three different factors on twins’ trust and distrust trust behaviors: heritable factors (that is, genetic influences); shared environmental factors (common experiences of growing up in the same family and interacting with the same immediate peers); and unshared environmental factors (the siblings’ unique experiences in life).

For the research, 324 identical and 210 fraternal twins were asked them to decide how much money to send to another study participant (representing trust) and another task that asked them to decide how much money to take away from another participant (representing distrust).

Identical twin pairs behaved more similarly than the fraternal twin pairs in their trust behaviors but not their distrust behaviors, suggesting that genetics influence trust, but not distrust.

Overall, analyses estimated that trust is 30 percent heritable, while distrust is not at all heritable.

Do twins live longer because they’re so close?

Meanwhile, the estimated contribution of shared environment to distrust was 19 percent, while shared environment didn’t contribute at all to trust.

Unshared environment—or the twins’ independent experiences in life—had the biggest impact on both trust and distrust, with unshared experiences contributing 81 percent to distrust and 70 percent to trust.

In other words, whether a person has a propensity to trust or distrust is not inherited or commonly socialized. Instead, it’s influenced by unique experiences in life.

“We all have a stock of past experiences that we draw on to help determine how we are going to behave in different situations, and future research should look at what particular types of life experiences could be the most influential on trust or distrust,” Reimann says.

“Disposition to trust, however, is not a product of experience alone; genetic influence is also significant. But we don’t see the same genetic influence with distrust.”

Oliver Schilke, assistant professor of management and organizations at the University of Arizona, and Karen S. Cook, a sociologist at Stanford University, are coauthors of the study.

Source: University of Arizona