Over the past decade, a growing number of studies have begun to ask the incredible: Can we find the genetic basis for who we are? Each time a new study comes out, news outlets report that a new gene has been found: there's the depression gene, the criminal gene, or the cuddly gene. Last week, my colleagues and I reported one such finding. We found that people who had two copies of the G version of the oxytocin receptor gene were seen as more trustworthy, compassionate, and kind than carriers of the A version of the gene; complete strangers made these judgments after watching just 20 seconds of behavior. Oxytocin is a neuropeptide-a chemical messenger in the nervous system-which has been implicated in empathy, trust, and sacrifice, along with more negative emotions as well, such as envy and boasting. Oxytocin operates through the usage of specific receptors in the brain that are themselves regulated by the oxytocin receptor gene. Thus, the reasoning goes, genetic variation in the oxytocin receptor gene can cause differences in the receptor, and affect the functionality of oxytocin; this can potentially explain why some people are kind and others are not. Not surprisingly, many of the stories written about our paper declared that we had discovered the "empathy gene."
But that's not quite right. To a certain extent, it is true that genes lay the foundation for who we are. After all, human beings are biological creatures (we are not rocks) and genes are the building blocks of our biological hardware. Our minds are fundamentally predicated on the existence of this biological hardware, so our genes are foundations for who we are. But this is a far cry from declaring a particular gene is responsible for a particular personality trait. Ultimately, many genes are going to be involved in creating the biological hardware that supports any particular personality trait or behavioral pattern. Therefore, we'd have to say there are empathy genes rather than an empathy gene. Even more critically, there are many, many non-genetic factors that are going to influence who we are. Our early childhood experiences, our current relationships, what happened 10 minutes ago, who we are interacting with-all of these variables play a crucial role in molding how we act and who we are. Any particular gene is only a single thread pulling you in a particular direction; there are many other threads that are also pulling you in one direction or another. How these many threads weave together is complex and poorly understood, but it is this precise weaving that ultimately results in who a person is.
When we consider any particular person, it's extremely difficult to make a claim about what he might be like based on knowing one gene. A person with two copies of the G version of the oxytocin receptor gene could be a psychopath or a saint; and the same can be said of a person with one or two copies of the A version of the gene. There are simply too many other factors in play that can mask, modify, or magnify the effect of the oxytocin receptor gene-or any other gene-on our personalities.