For those who try and fail to give up smoking, the problem may be more than a matter of willpower. A study Thursday says genes may also be to blame.
Researchers have known for some time that heredity plays a role in whether people smoke. However, the new work suggests that genes also influence the way they smoke, including whether they get by on a few cigarettes a day, develop pack-a-day habits, find it impossible to quit or shun cigarettes entirely.The study by Dr. Dorit Carmelli in the New England Journal of Medicine was based on surveys of 4,775 sets of male twins. She said she believes her findings apply to women, too.
The work may have implications for how doctors treat smoking. Those who have a genetic tendency to smoke may need more help quitting.
"Some smoke because they have a genetic tendency," she said.
Both heredity and environment - such as pressure from others to take up smoking - are thought to play a role in whether people smoke. Earlier studies have suggested that the tendency to smoke is about 50 percent inherited - a moderately strong influence.
But some doctors cautioned against making too much of the genetic influence.
Dr. Jack Henningfield of Johns Hopkins University noted that nationwide, the percentage of men who smoked dropped by half in recent years.
"In three decades, there has not been a change in the gene pool," he said.