Have attended a couple of recent conferences on the brain and addiction, Michael, where I attended workshops presenting research on the brain and addiction. Appears that the mechanisms of the brain gone-haywire in addiction are similar, whether the addiction is a substance or a behavior - gambling, exercising, shopping, video gaming, etc.

Addiction is clearly a multi-determined, complex and highly variable phenomenon. Like all things human (same holds for most other sentient beings,) countless variations contribute to individuality.

The severity of the addiction in terms of functional effects varies tremendously among folks addicted to the same substances, plus it would seem that some substances, such as nicotine and crack cocaine, tend to be more addictive for most people who suffer from addiction disease(s) than others.

Genes, nurture and experience all have powerful influences on the biology of the developing brain. The brain continues to develop, or at least to change, in response to all three factors throughout life. Learned behaviors are not "simply" learned behaviors, i.e. cognitive/thought processes. The brain changes both structurally and functionally in response to experience (including experience of the environment, which would also include experiencing the environment through the taking in of toxic chemicals in all the ways modern humans take in toxic chemicals - air, food, water, etc.) as well as genetics.

We are beginning to understand that efforts to understand human behavior are as complex as efforts to understand the universe - and the science of the universe is much more advanced.

I think it was Don Firth, on another thread completely unrelated to this one, who quoted a scientist friend involved in some aspect of astrophysics as saying, "The universe is not only stranger than we imagine, it is stranger than we can imagine."   I don't think the complexities of sentiency are beyond the capacity of at least some humans to imagine, but I do think the matrix is so complex and individual as to always contain uncertainty and mystery.

Identical twins have identical genes. Their experiences, beginning in utero are different, and so they are differentiated very, very early in development - based perhaps on nothing more in their physical positions within the womb. One rocks sideways when Mom walks, and one rocks vertically, perhaps.

Think about it.

There are no one-line answers to understanding addiction (or any other aspect of the all that goes into "being alive."    There are no "one size fits all" remedies to the problems that arise from the same. Research in many different areas related to understanding human behavior and experience is shedding light, but there is not only more light to be shed, there is much work to be done to understanding how to make meaning of what is seen under ever changing light. Once meaning is made that has at least some general applicability to the human race, the reality is that there are no "one size fits all" answers.

That is one of the reasons our species has thrived and multiplied. It may be that is one of the reasons we may fail as a species. Or, speaking in terms of species, that diversity may be what insures some remmant of our species survives and passes at least some of our genes onto future species. Diversity = adaptability.

Or not.

Quality of life and survival of species, over the very long range, are not necessarily mutually inclusive.