Smoking encompasses many different behaviors, from the initiation of smoking to the development of nicotine dependence, and finally cessation. Many variables influence smoking cessation. As people age, more quit smoking, and high education and income are strong predictors of successful quitting. The genetic risk factor on chromosome 15 that is associated with nicotine dependence, smoking quantity, lung cancer, and COPD appears to be a relatively specific risk factor for a smoker to become a heavy, nicotine dependent smoker. This chromosome 15 variant is not related to smoking initiation and experimentation, and it does not distinguish between never smokers and smokers [21].
