Sofia Quaglia

Identical twins have more similar views on environmental issues than non-identical ones, study finds

Some people are more environmentally conscious than others, and scientists say the reason could be in their genes.

Extinction Rebellion protesters take part in a blockade of an oil rig maintenance facility in Scotland. Photograph: Jeff J Mitchell/Getty Images

A study has found that identical twins had more similar views on conservation and environmentalism than non-identical twins. The researchers say this suggests there could be a link between people’s genetic makeup and their support for green policies.

“The goal is to understand why people are different, and such differences come from the combination of genes and environments,” said Chia-chen Chang, a research fellow at the National University of Singapore and lead author on the paper published in the journal BioScience.

“Considering genetic components provides us with a more holistic answer to this question, but genetic results are just about probability, not determinism.”

The researchers used data for more than 1,000 twins from the TwinsUK registry, the country’s largest twin database. They examined responses from identical and non-identical twins to questions about their concern for nature, environmental activism and how environmentally friendly their own behaviour was.

The results suggest that identical twins consistently had more in common across all three categories. This, the scientists say, suggests a link between people’s genetics and their environmental behaviour, as well as suggesting that there is some heritability to environmentalist traits.

“I initially didn’t expect to detect moderate heritability of these traits,” said Chang, though she noted that the results were supported by previous research about evolution which showed heritability for some altruistic and cooperative behaviours.

But the social environment somebody grows up in and is surrounded by still explains more than 50% of individual concern for nature, environmental activism, and personal behaviour, the researchers say.

“Heritability suggests there are genetic components. But heritability estimates are influenced by both genetics and environments,” Chang said. “Our environmental behaviour is probably more complicated than we think.”

Felix Tropf, a professor in social science genetics at the Center for Research in Economics and Statistics, who was not involved in the study, said there was a long way to go to understand the role of heritability in people’s environmental attitudes.

“I don’t think such a study is extremely useful for the issue,” he said. “It might motivate further research that at some point might be very useful, but first it’s important to understand that all we basically observe is that genetically identical twins are more similar than non-genetically identical twins in their attitudes toward climate change.”

In fact, although there may be many genes associated with climate attitudes, they might all do different things in different ways. “There is no one gene that makes you closer to nature or anything like that at all,” said Tropf. He also suggested the researchers should have included information about whether the twins in the study were frequently exposed to nature, as that would be expected to have an impact on the results.

“It’s good to analyse the influences on individual behaviour towards environmentalism, but in the end, climate change is a structural problem, a systemic problem and a political problem,” he said.