What causes substance abuse/chemical dependence?

Cultural and societal norms influence acceptable standards of substance use. Public laws determine the legal use of substances. The question of whether there is a normative pattern of substance use remains controversial. Substance-related disorders are caused by multiple factors including genetic vulnerability, environmental stressors, social pressures, individual personality characteristics, and psychiatric problems. However, determining which of these factors are primary and which are secondary has not been determined, in all cases.