Honestly I don't have enough time to write the whole science behind, nor the time to search right now for links and copy and paste.
However, the key behind the science from a naturopathic perspective, is that there is no such thing as a bad gene. Popular belief is that some diseases are hereditary, therefore they run in the genes, and therefore those are "bad genes" Well, theres no such thing. IF indeed existed a gene that is coded to be "bad", then the whole Darwinian theory of evolution of survival of the fittest would fall apart. Because under the theory of evolution nature does not allow a faulty copy to reproduce and pass those genes. Based on the theory, if a gene was coded to be bad, then there would be every day less and less specimens with that gene, because it would be naturally selected.
In our world, is the opposite. Every day we have more and more, more and more of those specimens with "bad genes", Like if "spontaneously" nature was randomly deciding to throw bad genes in the chain to increase things like parkinsons, alzheimers, autism, addictions, etc.
Why is that? Because again, there is no such thing as a bad gene. Instead, what we have is "MUTATED GENES" Its mutated genes what cause these issues, and all those mutations occur mostly from oxidative damage. Environmental factors like exposure to harmful chemicals, fumes, radio waves, radiation, microwaves, etc. Also from other ways like ingestion of harmful chemicals, drugs, etc. However, the body has its own mechanism of defense. Through key essential nutrients like Selenium plus a determined amount of antioxidants that usually is standardized by naturopathic doctors as 200,000 ORAC points daily, the body is able to combat most of the free radicals in the body. The amount of antioxidants necessary is different depending on the lifestyle of each individual. The sad reality is that THE VAST MAJORITY do not consume the necessary amount of antioxidants to prevent all that inflammation, oxidative damage, and ultimately gene mutation. Once those mutated genes form, they can easily be passed from one generation to another.
As far as I understand is very difficult to reverse the mutation of a gene in one generation, however, most of the symptoms can be managed through nutrients. In the case of the brain, I know for a fact because I cured myself years ago from a severe anxiety disorder. In my case was not a genetic mutation, but caused by lifestyle factors. Of course allopathic doctors wanted to put me on anti panic and anxiety medications, but I refused to live on drugs forever. I rather researched and studied the medicine that is denied to us by the government and realized that most weird brain behaviors are cause mostly by severe cholesterol and fat deficiency. Of course this has to go along with the right amount of essential minerals, vitamins and amino acids. Once I put this on track, I cured myself forever in a matter of a few months. I am positive that somebody with the addiction to smoking can perfectly stop if a healthy environment for the brain is created.
I personally reject and refuse the use of drugs as part of a treatment to a chronic condition, including an addiction. Drugs have their use in very specific and precise situations but certainly NOT in the irresponsible way they are prescribed in our for-profit market.