Just can't quit smoking? Blame it on your genes
Genes rather than feeble will power may be letting down people who try and fail to give up smoking.
Scientists have identified genetic variants that increase a person's likelihood of becoming a lifelong heavy smoker.
Those affected are more easily hooked as teenagers and quickly progress to smoking 20 or more cigarettes a day. As adults, they find it harder to quit the habit than people with a different genetic make-up.
Researchers studied 1,000 New Zealanders from birth to 38 to identify those at a greater genetic risk of smoking.
Participants with a high-risk genetic profile were more likely to smoke as teenagers. At 38, they had smoked heavily for more years, were more susceptible to nicotine addition, and were more likely to have failed in attempts to quit.