Skip to content

When you choose to publish with PLOS, your research makes an impact. Make your work accessible to all, without restrictions, and accelerate scientific discovery with options like preprints and published peer review that make your work more Open.


Our genes help us make tough moral decisions

Today we published a paper about how genes help control decision-making in morally ambiguous situations. Before I even got to the results section, though, I was side-tracked by the premise. Apparently researchers have already established that people respond differently to moral decisions depending on how the outcome is reached, even if the end result is the same.

To illustrate, here’s the example given in the paper. Let’s say there are five people tied to a train track, and there’s a runaway train barreling toward them. Now imagine that you can reroute the train so it doesn’t hit those five – but there’s a single person tied to the track on the new route. Given this scenario, people generally agree that sacrificing the single person to save the five is acceptable. On the other hand, the same outcome – losing one to save five – is generally deemed unacceptable if the only way to reroute the train is by actively moving that single person, intentionally putting him or her in harm’s way.

The numbers are the same. But, in the first case, the one person is a victim of what is called “foreseen” harm, which is considered an unfortunate but acceptable side effect, while in the second case, he or she is a victim of “intentional” harm. This intention means that it is usually judged to be impermissible.

Now, back to the paper. It turns out that this well-established pattern can be influenced by biological factors as well. Not surprisingly, brain injury can cause decisions that deviate from the norm, but so can other factors, like selective serotonin reuptake inhibitors (SSRIs). The authors of today’s paper, led by Abigail Marsh of the Georgetown University psychology department, took this SSRI observation a step further and investigated how genetic differences in a serotonin transporter gene correlate with moral decision-making. They found that the participants’ genotype – which corresponds to how active their serotonin transporters are – correlates with their stance toward foreseen but unintentional harm. Just like people taking SSRIs, individuals with less active transporters are less likely to endorse decisions that harm an innocent victim, regardless of how many people might be saved as a result.

It all leaves me wondering – which genotype am I?

Leave a Reply

Your email address will not be published. Required fields are marked *

Add your ORCID here. (e.g. 0000-0002-7299-680X)

Back to top