We often talk about empathy as though it's something we can all gain more of if we just try hard enough - like muscle, or a higher score in Candy Crush. But a new study out today provides new evidence for the idea that individual empathy differences are determined, at least in part, by genetics.
Photo: Michael Brace
There are two main types of empathy: Cognitive, which is the ability to recognise and understand others' feelings and thoughts, and affective, which is the ability to respond appropriately to those observations. It's often measured with an empathy quotient (or EQ) test that asks the subject to self-report their empathetic abilities by using a rating scale for statements such as "I adjust my behaviour depending on who I am interacting with" and "I like learning new things".
Thanks to major biotech developments in the past couple of decades, researchers have increasingly been looking to DNA to understand things such as cancer risk, autism, disorders such as schizophrenia, and even sexuality. These efforts are often billed as a search for "the cancer gene" or "the autism gene", but the findings are rarely so on the nose. Scientists have been looking for links between genetics and empathy for more than a decade, and while they have often found signs of a connection, they're still a long way from identifying any one "empathy gene". Today's study, published in the journal Translational Psychiatry, brings them a bit closer.
The study, completed by a team of scientists from Cambridge University, the Institut Pasteur, Paris Diderot University and the French National Center for Scientific Research, along with genetics experts from 23andMe, is the largest genome-wide association study of empathy yet. 23andMe provided the saliva of 46,861 customers, and all of the subjects also completed an online EQ test.
Many Genes With Small Roles
The new findings validated some old results, and added some new data to the field. The average self-reported EQ score was 46.4 out of 80, which is in line with previous studies. Women scored higher than men, and older participants scored higher than young participants, both of which were also in line with previous research. The findings also suggest a "narrow but significant" correlation between DNA and empathy variance. Put simply: DNA appeared to be responsible for about 11 per cent of the differences in people's self-reported empathy abilities.
But it isn't clear exactly how those DNA differences cause differences in empathy. The investigators looked at whether those DNA differences, called SNPs, occurred in specific genes, and found that two genes were especially likely to contain the relevant SNPs: SEMA6D, which affects neuron growth, and FBN2, which helps with the development of fibres in skin, ligaments and blood vessels. But looking at all the SNPs in all the genes, no particular function stood out when looking at the full data set. For example, if all the differences had been in genes relating to neuron growth, that might tell us something. But the scattered nature of the results may mean that genes affect empathy in a way we don't yet understand - or that they aren't really players in the empathy game at all. In other words, the search for a specific empathy gene continues.
One of the researchers, Professor Thomas Bourgeron of Paris Diderot University, says the findings are a sign that the science is moving in the right direction, toward understanding how genes affect how we see and interact with the world.
"These results offer a fascinating new perspective on the genetic influences that underpin empathy," he said. In the likely situation for complex traits such as empathy, each gene plays a small role, which Bourgeron says makes it hard to identify their specific functions. The next step, he said, "is to study an even larger number of people, to replicate these findings and to pinpoint the biological pathways associated with individual differences in empathy".
What Genes Have to Do With Empathy
So how might genes influence empathy? Previous research gives us some clues. Genes give the body directions for making different kinds of proteins. Some of these proteins are receptors for hormones such as oxytocin (often known as the "happy hormone" or the "love hormone") and vasopressin, which have both been found to influence social behaviour. It might be that some people have more sensitive receptors for these hormones, and thereby more empathy, thanks to their genes. One recent meta-analysis found that in six of seven studies of twins, at least one age group was found to have genetic differences that contributed to differences in empathy. Another found that genetic factors accounted for 35 per cent of the difference in people's empathy. (Read about these studies and others here.)
The new study also validated previous findings about empathy differences in people with autism, schizophrenia and anorexia. While the study did not find specific genes associated with both empathy and the three conditions, it did find a connection between EQ score and all three of those disorders.
Professor Simon Baron-Cohen of Cambridge, who contributed to the study, said the findings should help us understand people who struggle to imagine others' feelings. "This empathy difficulty can give rise to a disability that is no less challenging than other kinds of disability," he said. "We as a society need to support those with disabilities, with novel teaching methods, work-arounds or reasonable adjustments, to promote inclusion."
While the study also confirmed that women are more empathetic than men on average, that was only true in the results of the self-reported empathy quotient survey; there was no clear gene difference that correlated with EQ survey differences between men and women. This, the researchers say, suggests that empathy differences between men and women likely have more to do with how we're socialised than with our DNA.
What We Still Need to Learn
While big data is useful for research, it can only go so far when dealing with the brain. The study found no clear evidence pointing to a specific gene, or piece of a gene, that affects empathy. They note that this may be because the dataset is still too small - a common problem with genome-wide association studies.
"Even with this amount of data from 23andMe, it's still not enough. We need even bigger data," said Dr Jean Kim, a clinical assistant professor of psychiatry at George Washington University, who was not involved in the study. "There are no simple genetic biomarkers in behavioural conditions that allow you to go to one small mutation or gene and easily turn it on and off. Given the complexity of the brain, there will be no quick and easy answers found."
It's also important to note that nearly all of this research's subjects were of European ancestry (a common data problem with personal genomics companies such as 23andMe).
And since genome-wide association studies such as this one require a huge amount of statistical tests, they have gotten something of a reputation for their larger-than-average potential for false-positive results.
Still, Kim and others are encouraged by this progress toward determining whether empathy is partly inherited through our DNA. "Studies like this one are part of many small steps toward better understanding of human behaviour," she said.