The Hungarian researchers Ádám and Dávid Tárnoki have an unusual advantage when recruiting participants for twin studies. If the process is likely to be laborious or time consuming, and participants need a little extra encouragement, they look to their most reliable twin pair to demonstrate: themselves. “We had a sleep study where the twins had to sleep overnight at Semmelweis University and undergo many blood tests and sleep tests, with many cables on their bodies,” Ádám told Times Higher Education. “It was not so convenient, so we decided to be the first twin pair and share our experiences. Almost 80 or 90 twin pairs ultimately participated.”
The Tárnoki brothers, alongside Júlia Métneki and Levente Littvay, began work to revive the defunct Hungarian Twin Registry in 2006, establishing an official population-based registry in 2021. Today, the registry has more than 10,000 enrolled twins, enabling the Tárnokis to conduct imaging-based studies. Ádám is also nearing the end of his term as president of the International Society for Twin Studies; when he steps down, Dávid will succeed him.
“Why are twin studies special? Because the twins are born at the same time, they spent time in utero in the same environment, most of them share their early life until they become adolescents, so the common environment is the same,” Ádám explained. Studying twins enables researchers to examine the environmental and genetic influences on the development of diseases or traits; in recent years, the Tárnokis have studied the heritability of atherosclerosis, a key risk factor for heart attacks and strokes, as well as the impact of the gut microbiome on the development of dementia and breast cancer.
Twin research, however, is not the brothers’ primary occupation: both are radiologists at Semmelweis University’s medical centre, while at the National Institute of Oncology Dávid leads the imaging centre and Ádám is head of the radiology department. Both teach at Semmelweis University and supervise PhD students. “It’s an advantage to be twins because we can share the work. One part of the job is performed by Ádám, the other by me,” Dávid said.
In secondary school, the twins shared classes: “We studied together from one book, so we could discuss it and more easily prepare for exams,” Ádám said. Next came medical school at Semmelweis University, before they specialised in radiology. “We share 100 per cent of our genes as monozygotic twins. We have the same interests,” Dávid said. But they didn’t pursue completely identical careers, Ádám said: “I study nodular and oncological lung disorders, and Dávid studies interstitial lung disease.”
Though they spent most of their working week together, the Tárnokis said, they rarely tired of each other or felt a sense of competition. “We don’t fight, or it’s extremely rare, because we’ve seen that it makes no sense to do it. It’s not advantageous to us to fight,” Ádám said. “I know what he’s thinking because we usually think the same, or at least very similarly. This is why our working pair is more effective.”
Still, the brothers said, they spent time apart at the weekends, typically devoting them to their families. Both twins are married; each brother has two young daughters. “It’s funny,” Dávid said. “We have the same trajectory.”
