After seeing the recent ups and downs of Wall Street, I was fascinated to see a new study in the Proceedings of the National Academy of Sciences by an international team of researchers that has demonstrated for the first time that genes exert an influence on people's behavior in a very common experimental economic game.
The Nobel Laureate Jim Watson once quipped that there were only molecules and everything else was sociology. I don’t think that he was being altogether serious, but he did highlight a yawning chasm between different ways of describing human experience.
Social scientists have been a bit reticent about acknowledging a role for genes in economic behavior. But a study by David Cesarini, from the Massachusetts Institute of Technology’s Department of Economics and colleagues in Sweden indicates that there is a genetic component to people's perception of what is fair and what is unfair.
The researchers looked at the ultimatum game, in which a proposer makes an offer to a responder on how to divide a sum of money. This offer is an ultimatum; if the responder rejects it, both parties receive nothing.
Because rejections in the game entail a zero payoff for both parties, theories of narrow self-interest predict that any positive amount will be accepted by a responder. The intriguing finding in the laboratory is that responders routinely reject free money, presumably because they feel that they want to punish proposers for offers that they think are unfair.
To study genetic influence in the game, the researchers recruited twins from the Swedish Twin Registry, and had them play the game under controlled conditions. Because identical twins share the same genes but fraternal twins do not, the researchers were able to detect genetic influences by comparing the similarity with which identical and fraternal twins played the game.
The results suggest that genetic influences account for as much as 40 percent of the variation in how people respond to unfair offers. This is much larger than the effect of common environmental influences such as upbringing.
The research indicates that many of our preferences and personal economic choices are subject to substantial genetic influence, and it will be interesting to see how they interact with social and environmental factors.