A smoker is more likely to kick the habit if a spouse, friend, co-worker or sibling did..

May 22, 2008 -  A team of researchers who showed that obesity can spread person-to-person ( NEJM 357(4):370-379, 2007) has found a similar pattern with smoking cessation. Not surprisingly, the greatest influence was seen in close relationships. When a spouse stops smoking, the other partner is 67 percent less likely to smoke. Similarly, when a friend quits, the odds of the other continuing drops by 36 percent. The odds are similar among co-workers and siblings. The findings back up previous studies showing that peer influence plays a key role in people's decision to stop lighting up and provide evidence that the "buddy system" used by smoking cessation, weight loss and alcoholism programs to change addictive behavior works. References: The Collection Dynamics of Smoking in a Large Social NetworkN. Christakis and J. Fowler, NEJM 358(21):2249-2258, 2008;Smoking is addictive, but quitting is contagious", EurekAlert.org, 5/21/2008. Researchers say smokers tend to quit in groups by ALICIA CHANG AP Science Writer, MercuryNews.com