Appreciation of Nature – A Heritable Characteristic?

A new twin study has explored the extent to which our genetics shape our desire to spend time in nature. The results are published in PLoS Biology.

Spending time in nature – a genetic trait?

Sometimes there’s nothing the heart yearns for more than a walk in nature, to bask in the fresh air and take in our surroundings. Research has shown that spending at least 120 minutes in nature per week is associated with good health and wellbeing. Lack of time in nature was arguably one of the most difficult aspects of the COVID-19 lockdowns, for many people.

The amount of time we spend in nature is subject to many different factors, including where we live (nature opportunity) and our personal desire to experience nature (nature orientation).

In addition to environmental factors that affect nature orientation, it has been hypothesized that our genetic code – the DNA molecules we inherit from our parents – could have an impact. However, this hypothesis had not yet been tested, until now.

Researchers from the National University of Singapore have conducted a large-scale study of UK twins to estimate the moderate heritability of nature orientation. “Twin studies are useful to estimate how heritable a trait is because of the difference in genetic similarities between identical vs non-identical twins,” Chia-chen Chang, former research fellow at NUS and current post-doctoral research fellow at the University of California Davis, said. “In general, identical twins (monozygotic) share 100% of their genes while non-identical twins (dizygotic) share 50% of their genes. If a trait, such as the desire to be in nature, is clearly more similar between identical twins than non-identical twins, it suggests that this trait is heritable.”

A twist on nature vs nurture

Chang and colleagues surveyed 1,153 twins from the TwinsUK registry. They gathered responses from 666 pairs of monozygotic female and 98 male twins, 350 pairs of dizygotic female and 30 male twins, and 9 dizygotic opposite sex twins. The survey aimed to examine how much genetic vs environmental influences can explain variation in nature orientation, urbanization of the individual’s home location and four aspects of nature experience (including frequency, duration of visits spent in public nature spaces and the frequency and duration of time spent in domestic gardens).

After controlling for age and sex, the research team created a model that would allow them to pick apart the genetic and environmental correlations between specific phenotypes.

Chang and colleagues found that, overall, environmental factors were more important than genetic factors in shaping an individual’s appreciation of and tendency to visit nature. “Some potential key environmental factors are, among others, educational experiences, social norms and whether or not we live in a biodiverse area,” Chang explained.

However, while environmental factors contributed to nature orientation, so did the participants’ genetics. Identical twins had more similarities with each other in terms of how frequently they spent time in nature compared to non-identical twins.

“In our daily life, we can see that some people are more connected to nature and interact with nature more often other people. Why is that? Does it come from genetic factors? Or it is because of the environments that we have experienced? The answer is both, and our personal experience is likely to be more influential than genetic factors,” Chang.

Heritability ranged from approximately 46% (nature orientation) to 34% (frequency of garden visits). This heritability figure declined with age, because, as Chang described, environmental influences became more important the older the participants were. “It may be because some additional factors are influencing the older adults but not young adults. Or it can be same factors, but they impact older adults more than young adults. It is also possible it comes from the difference in the generation per se, not age specifically. We do not know for sure,” she said.

Future perspectives

A limitation to the work, highlighted by Chang, is that twin analyses often rely on assumptions: “One of the assumptions is equal environment similarities. We assume environmental similarities to be equal for identical twins and non-identical twins. If identical twins experience more similar environments than non-identical twins, for instance, identical twins tend to have same groups of friends of join in on the same activities, but non-identical twins tend to have different groups or join different activities.” If these differences do occur, its possible for researchers to overestimate the heritability.

Nonetheless, the researchers emphasize that the data is useful for demonstrating the importance of environments. By providing more opportunities for rich nature experience, we see that individuals interact with nature more often, and reap the associated health wellbeing benefits.

As for advancing this work, Chang and colleagues are interested in exploring how exactly experiences in nature could encourage environmental concerns and behaviors. “There seems to be mixed evidence to this question, and there is still much to explore,” Chang concluded.

Reference: Chang C-c, Cox DTC, Fan Q, et al. People’s desire to be in nature and how they experience it are partially heritable. PLoS Biol. 2022. 20(2): e3001500. doi: 10.1371/journal.pbio.3001500.