Addiction is the ability of the brain to proceed, process and act upon pleasurable experience. The brain creates pleasurable experience, it brings reward and one can remember it. Addiction is pleasure unwoven.
I feel the film narrator also gave a good explanation of the five theories of addiction- the Genes, Reward, Memory, Stress and Choice.
We are all venerable to addiction, but in some people, their genes make them more venerable but something in the environment has to turn those genes on. Parents with addiction genes pass the genes down to their