Those who say they cannot quit smoking, no matter how hard they try, could now blame their genes.
Scientists have discovered a brain pathway which, if not functioning correctly, can lead to an uncontrollable desire to smoke, reports dailymail.co.uk.
The fault lies in a receptor protein that is normally activated by the nicotine in cigarettes and dampens the desire for yet more of the drug.
The team found that when rats were genetically changed to block the protein, they consumed far more nicotine.
Professor Paul Kenny, of The Scripps Research Institute, Florida, said: “These findings point to a promising target for the development of potential anti-smoking therapies.”
“The data could explain why some people are far more vulnerable to the addictive properties of nicotine and more likely to develop smoking-associated diseases such as lung cancer,” he added.