German scientists have discovered that a variation in a certain gene corresponds with a greater propensity to give money to charitable causes. The researchers looked for variants of the COMT gene, which is involved with the release of dopamine.

Variations of the COMT gene, COMT-Val and COMT-Met, are equally common among human populations. Prior to giving participants money to donate to charity, researchers at the University of Bonn swabbed their cheeks to see what variation of the gene they carried. From the University of Bonn:

The researchers working with the psychologist Professor Dr. Martin Reuter invited their students to take a "retention test": The roughly 100 participants were to memorize series of numbers and then repeat them as correctly as possible. They received the sum of five Euros for doing this. Afterwards, they could either take their hard-earned money home or donate any portion of it to a charitable cause. This decision was made freely and in apparent anonymity. "However, we always knew how much money was in the cash box beforehand and could therefore calculate the amount donated", explains Reuter.

[...] In these analyses, they focused on one gene, the so-called COMT gene. It contains the building instructions for an enzyme which inactivates certain messengers in the brain. The most well-known of these messengers is dopamine. [...] In the case of people with the COMT-Val variant, the associated enzyme works up to four times more effectively. Thus considerably more dopamine is inactivated in the brain of a person with this variant. This mini-mutation also has effects on behavior: "Students with the COMT-Val gene donated twice as much money on average as did fellow students with the COMT-Met variant", explains Reuter. This is the first time that researchers have been able to establish a connection between a particular gene and altruistic deeds. However, it was already known from studies on twins that altruistic behavior is also partly influenced by our genes.

You can read Dr. Reuter's team's research abstract at Social Cognitive & Affective Neuroscience.