A healthy adult lifestyle is less important for fending off heart disease than your childhood, a study has suggested.
Around two-thirds of the influence behind one type of coronary artery blockage is due to upbringing and childhood, the study stated, whereas a third is due to adult lifestyle choices, such as smoking.
Researchers looked for the main cause of troublesome blockages in coronary arteries, which can cut off the supply of oxygen to the heart muscle.
They focused on soft noncalcified plaques, which form quickly and are more likely to burst and cause a heart attack than harder blockages, which take longer to develop.
Dr Ádám Domonkos Tárnoki, study author and a radiologist at Semmelweis University in Budapest, said: "These fatty plaques are more dangerous, as they can rupture more easily leading to acute coronary occlusion and heart attacks.
"The calcified plaques, although they can also cause stenosis in coronary arteries, are not so prone to cause acute cardiac events.”
Factors such as upbringing and family and social background were found to have a 63 per cent influence on their formation.
Things associated with an unhealthy adult lifestyle like smoking, drinking and inactivity were grouped into a category called “unique environmental factors” and accounted for just 37 per cent of the risk.
A total of 98 twin dyads aged between 45 and 65 years old were studied, including 60 pairs of identical twins and 38 non-identical sets.
Each twin was asked to complete a detailed questionnaire about their upbringing, family background and lifestyle.
This involved answering questions such as where they grew up, what their diet was like as a child, if their parents had any illnesses and if they now smoke or exercise regularly.
The scientists then conducted heart CT scans on each person to establish the build-up of plaques in their coronary arteries.
The study also found genetics play the biggest role in the development of calcified plaques, the less dangerous form of coronary artery blockage.
Dr Dávid László Tárnoki - study co-author, twin brother of Adam Domonkos Tárnoki and also a radiologist - added: "Early lifestyle intervention can have a significant relevance in preventing coronary artery diseases.”
While they found noncalcified plaques were mostly driven by upbringing, the same was not true for the calcified plaques, which are heavily influenced by genetics.
Fifty-eight per cent of the coronary artery calcification score and 78 per cent of the calcified plaque volumes were determined genetically, the scientists write in their paper, published in the journal Circulation: Cardiovascular Imaging.
Dr Pál Maurovich Horvat - director of the Medical Imaging Centre at the Budapest Semmelweis University, who led the study - said: "It has been known from previous studies that genetics has a strong influence on the formation of calcified plaques, but there has been much less data about the heritability of noncalcified plaque volume.
"The aim of our research was to evaluate the role of genetics versus common and unique environmental factors in the development of calcified and noncalcified plaques, by using coronary computed tomography angiography in adult twin pairs without known coronary artery disease."