Some people seem to be more prone to addictive behavior than others. Scientists and researchers do not have all the information as to what makes one person more easily addicted to something like oxycodone than another-all they do know are that some people can successfully take a course of oxycodone, stop, and never take it again, while others take a course of oxycodone and never stop taking it. What makes these people different is likely genetics combined with their upbringing, but what fraction of addictive behavior is learned and what fraction is genetic is, as of yet, unknown.
Source:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2851054/
