Scientists throughout the world, specially Ming Li and the research team in Virginia, have conducted experiments between 1994-2014 to assess possible genetic influences on smokers. 22 different studies were performed with over 9, 500 smokers involved, and the results were revolutionary. These scientists specifically targeted a Taq1A sequence of DNA in the human genome. Smokers with the A2/A2 variation of this DNA sequence found it easier to quit smoking--the "cold turkey" and instantaneous quitters. Smokers with other variation of the Taq1A gene found it very difficult to quit, often committing and getting hooked back to the habit. The sequences of DNA influence the amount of dopamine being produced in the brain in response to the nicotine levels in blood. Consequently, the A2/A2 individuals release less dopamine, making nicotine less addictive; therefore, it becomes easier to quit.
I found this research very interesting. I have always wondered why some individuals can quit smoking seemingly much easier than others. Professor Edelmen, a professor of medicine in New York, states, "There's a huge variability in the ability to quit smoking…" Although this is true, geneticists have discovered a genetic influence on smokers that makes sense biologically.