Addiction and mental health are effected by your genetics. Those neurotransmitters or lack of neurotransmitters come from your inherited genes. These are what will affect you getting and staying sober.To get and stay sober there is a balancing act that must occur in the neurotransmitter system. It is this that is unique to the individual and this coupled with the drugs of abuse that work on these systems is what makes withdrawal so difficult.
Detox and withdrawal are affected by the neurotransmitter systems that the drugs have affected. Your genetics affects how you respond after the drugs and/or alcohol are withdrawn from your system. There is a great book called Brain in Balance by Dr. Von Schieff that explains this with case studies. In this book it is explained how detox does not have to be horrible or painful. But you do need a provider who knows what he/she is doing. Same thing happens when you take the drugs or alcohol out . Your body wants more to re-balance what it has known. There is a physiological response that you develop and its a craving to fix the imbalance.
Addiction and mental health recovery are a priority if you want to live life. It can be done but you need help to recover.The help is out there just ask.