Here we go again? It is good to hear from you.
I have seen the assorted posts about genetic proclivities to nicotine addiction. I also read several studies about it that were published around 2007 - 2009. Honestly, my reaction has always been a shrug and "Yeah, okay, whatever."
People have known from the time we first started deliberately fouling or lungs on a regular basis (As opposed to ceremonial/ritual smoking) that nicotine (or "something" before we isolated nicotine) was physically addictive and that some people were more easily/deeply addicted than others. The same is true with virtually every other drug from alcohol to heroin.
The assorted studies indicating a genetic inclination to becoming addicted to nicotine, alcohol, or anything else have only confirmed what we already knew. Yes, now that we know what to look for, one could have a test done to determine whether or not her/she had a genetic predisposition toward physical addiction to nicotine. Since it is the physical effects of repeatedly filling your lungs with tar and a thousand other poisons, of repeatedly starving your heart of its necessary ration of oxygen, and assorted cellular mutations that make smoking deadly, not addiction, I have no idea why someone would want such a test; but they could get it if they did.
I do not deny for a moment that nicotine is physically addictive. I doubt that any honest smoker would. In my opinion, however, the physical addiction is so inconsequential, even for those unfortunate souls with a genetic disposition to it, that it warrants only passing acknowledgment. From a personal perspective, I would suffer far greater physical discomfort if I were to deny myself my daily ration of caffeine; and any smoker who has gone through even mild DT's will tell you they are far worse than the physical discomfort of nicotine withdrawal.
I believe that our awareness of nicotine withdrawal is heightened by our psychological addiction to smoking. As a result, the physical discomfort a smoker feels when denied his/her drug is magnified. Not that it isn't there, it is, but it seems a lot worse than it is. Of course, when we finally get to have a cigarette, the the physical gratification is also magnified and all the more satisfying.
So, yes, there is a clear physical explanation for why people continue to smoke after beating their lngs into submission and there is a physical reason why they find it unpleasant when they are deprived of their drug. As far as I'm concerned, it is only one very small facet of a very complex phenomenon.