Earlier this week, in questioning the significance of a "scientists find internet-addiction gene" story, I conceded that the scientific study in question did find something interesting: A gene that seems to be (very modestly) correlated with internet addiction also plays a role in nicotine addiction.
Maybe this nicotine connection is what prompted the German scientist who was the lead author of the study to declare that, thanks to his work, we now know that "internet addiction is not a figment of our imagination." After all, if a gene involved in a manifestly chemical addiction, like nicotine addiction, is also involved in something people doubt is literally an addiction, then that should remove the doubt, no?
No. Whether heavy internet use deserves to be called an addiction or just a hard-to-break habit is a question about a behavior pattern and its attendant psychological states. To answer it we ask such things as how strong the cravings for the internet are, what lengths a person will go to in order to satisfy them, and so on. But even if we decide, after answering such questions, that a given person's internet dependence amounts only to a habit, and doesn't warrant the "addiction" label, it still makes sense that genes which mediate chemical addictions--nicotine, cocaine, whatever--would be involved.
To see what I mean by this is to see that, yes, a susceptibility to internet addiction (or heavy internet habituation, or whatever you want to call it) is "in the genes" -- but it's in lots and lots of genes, and it's in the genes of all of us.
The reason for this, naturally enough, lies in the process that created our species. Human beings are biochemical machines "designed" by natural selection to, among other things, form habits. In particular, we're designed to form habits that helped our ancestors survive and get genes into the next generation -- such habits as eating meat or fruit or having sex with auspicious mates or impressing people or even gathering tactically useful information about people (i.e., gossip). The habit-forming machinery involves the release of reward chemicals, such as dopamine, that make us feel good upon attaining these goals--upon eating fatty food, sweet food, having sex, hearing people laugh at our jokes or marvel at our exploits, hearing good gossip, etc.
Now, the environment that natural selection designed us for -- a hunter-gatherer environment -- didn't feature endless and readily available supplies of tasty food, and it didn't present constant and easy chances to mate or impress peers or pick up good gossip. Our ancestors had to spot their opportunities and then do some work to get these things--and only then, upon achieving these goals, would they get the chemical rewards that would bring pleasure and thus encourage them to repeat this work in the future. So it took some effort to reach that magic moment when, with your goal attained, chemically mediated gratification would ensue.
In the modern world, there are shortcuts to getting these rewards: Just ingest chemicals -- nicotine, cocaine, heroin, whatever -- that intervene directly in the chemical reward system, sometimes by mimicking neurotransmitters. For example: acetylcholine is a neurotransmitter that, when it binds to a neuron, can have various gratifying effects, including the release of dopamine. And nicotine can bind to certain kinds of neuronal acetylcholine receptors and elicit some effects that acetylcholine would bring. And there's some evidence (though here I'm approaching the limits of my comprehension of the science) that people with a particular variant of a gene involved in building acetylcholine receptors are more susceptible to nicotine addiction than other people.
Anyway, the main point is this: the biochemical mechanisms (including genes) involved in chemical addictions will naturally be the mechanisms involved in habit formation more generally since habit formation is what they were originally designed for. So when this German scientist announced triumphantly that a gene which seems to have a modest correlation with heavy internet use is a gene that may play a role in nicotine addiction he had told us (1) nothing that should surprise anyone; and (2) nothing that settles the question of whether this heavy internet use deserves to be called an "addiction" or merely a "habit." Either way, whether it's a habit or an addiction, it is going to involve pleasure-dispensing biochemical mechanisms of the sort that can get us addicted to such chemicals as nicotine and cocaine--because, again, it is through such pleasure-dispensing mechanisms that habits in general form.