A study based on blood samples from more than 55,000 Danes shows a direct correlation between smoking and mortality. A special gene variant increases the risk of heavy smoking, researchers report. “There is a lot to suggest that you can be genetically predisposed to heavy smoking. Smokers carrying a special genetic mutation have a higher tobacco consumption, which is, of course, very harmful for their health — and they have a 14 percent higher risk of dying before other smokers,” one researcher.