The Heritability of Affection and "Skin Hunger" in COVID-19 Times

At some point or another in life, it's quite probable that you will encounter a "hugger".

The friend that eagerly greets you with open arms each time you see them, the family member that squeezes you a little too tightly so that you can't quite breathe or perhaps the stranger you find yourself in arms with when you initially planned a handshake.

On the flipside, there are the individuals that really detest hugs, and are keen to avoid displays of physical affection at all costs. But why is this? How does such variation in social behaviors come to exist? It's a question buried in the infamous nature versus nurture debate, and for which science, or more specifically, genomics, seeks to provide some insight.

"In my field, there is a really strong underlying assumption that whenever we see differences in a trait level in people's social behaviors – like how talkative they are or how shy they are or how affectionate they are – those differences are learned; they're a function of the environment," said Kory Floyd, Professor at the University of Arizona Department of Communication in the College of Social and Behavioral Sciences, in a recent press release.

Floyd is the leader of a new study that has been published in Communication Monographs that, upon recognizing that some people are more affectionate than others, asks what exactly accounts for that variation, and are there any genetic components to it?¹

"A study like this makes room for us to talk about the possibility that a number of social and behavioral traits that we automatically assume are learned may also have a genetic component," said Floyd.

Exploring human affection in twins

The study adopted a twin design to explore the research question. Twin studies offer a unique platform for scientists to investigate how environmental and genetic factors influence specific traits.

Why? Well, twins are typically (but not always) raised in the same household and thus are subjected to very similar upbringings and early life experiences. Their genetic similarities of course depend on what type of twins they are: identical twins (or monozygotic, MZ, twins) share 100% of their genetic material, whereas fraternal twins (or dizygotic, DZ, twins) share 50%.

Floyd and his team recruited a total of 464 pairs of adult twins for the study, comprising of 229 MZ pairs and 235 DZ pairs.

Each individual was asked to complete a questionnaire in which they rated a number of statements designed to measure how much affection they express and how much they typically receive, known as the Trait Affection Scale-Given and Trait Affection Scale-Received.

The researchers analyzed the data from the twins using a form of modeling known as ACE modeling, which they describe in the paper: " The primary goal of ACE is to model twins’ distinct genetic and environmentally related characteristics as latent factors that explain variance in individuals’ observed traits. That is, the goal is to use what is known about these unique dyads to determine why traits differ between individuals. The ACE approach allows researchers to estimate the extent to which trait variation in the human population is due to additive genetic traits (modeled as latent factor A), common environments (modeled as C), or unique environmental experiences (E) among the sample."

Study suggests levels of affection are partly heritable

If genetics did not play a role in levels of affection, it could be assumed that the scores of fraternal twin pairs would match the scores of identical twin pairs. However, in this study, that was not the case.

Rather, the scientists found that approximately 45% of the variance in trait expressed affectionate communication is heritable, whereas the remaining 55% of variance is attributable to nonshared environmental influences – at least in females. This data implies, to an extent, that there is a genetic component to affectionate behavior.

Why did the data differ for men and women? The researchers don't know for sure, but Floyd emphasizes that, generally, men tend to express less affection overall when compared to women: "When we measure people's tendency to be affectionate and to receive affection from other people, almost without exception we find that women score higher than men."

"The trait of being affectionate may be more adaptive for women in an evolutionary sense. There is some speculation that affectionate behavior is more health supportive for women than it is for men, and that it helps women to manage the effects of stress more than it does for men. That may be partly why women are more likely than men to inherit the tendency to behave that way rather than that tendency simply being a product of their environment."

Interestingly, the researchers found that twins' shared environments, how they were raised and their socioeconomic background, did not have much impact on how affectionate they were. Instead, unique environmental factors such as an individual's friendship groups and social experiences apart from their twin had more influence.

"It's not exactly what we would expect, but for many behaviors and personality characteristics – including how affectionate you are – what twins do and experience differently in their lives plays a much bigger role than anything they experience together," Floyd noted.

Of course, there are limitations to this study that must be considered. It relies on self-report data, which isn't necessarily the most valid method as individuals may not wish to honestly share their levels of affection over fears of how they may be perceived.

It's also important to note that the research findings are at the population level, not at an individual level. Not every woman's level of affection can be attributed to their genetics at exactly 45%, and a person isn't restricted to being affectionate to a certain level because of their genes.

Affection in COVID-19 times

Of course, in the current context of the COVID-19 global pandemic, physical affection has been extremely limited to halt the spread of the coronavirus SARS-CoV-2. Floyd has suggested there may be individuals that are experiencing a phenomenon known as "skin hunger".

"Just like regular hunger reminds us that we're not getting enough to eat, skin hunger is the recognition that we're not getting enough touch in our lives. Many people these days are recognizing that they miss getting hugs, they miss touch, and it's maybe the one thing technology hasn't really figured out how to give us yet," he said.

To this end, he advises a number of things people can do, including petting a dog or cat, cuddling your pillow or a blanket and practicing self-massage.

"None of these is a perfect substitute. But when being able to hug or hold hands with our loved ones isn't feasible or safe for us, these sorts of things are certainly better than nothing," Floyd concluded.

Reference: Floyd K., York C., and Ray C. D. (2020). Heritability of affectionate communication: A twins study. Communication Monographs. DOI: https://doi.org/10.1080/03637751.2020.1760327.