The nature vs nurture debate is a major source of argument between different approaches to understanding human behavior, including addiction.
Theories that base their understanding of human behavior on "nature," focus on characteristics that we are born with, like our genetic make-up, stable personality traits, and physical predispositions. In contrast, theories that base their understanding of human behavior on "nurture," emphasize those experiences that mold and change us throughout our lives, such as how our parents raised us, what we were taught at school, and our culture.
Although most experts agree that addiction involves a complex interplay between inborn characteristics (nature) and life experiences (nurture), the focus of research tends to emphasize one or the other. For example, a study looking at the effects of neurotransmitters on the process of addiction leans towards the "nature" end of the debate, whereas a study looking at peer pressure recognizes that "nurture" is also important in people's potential for addiction.
There are risks in relying too heavily on either nature or nurture when explaining addiction. If you believe that addiction is a purely physical process, you can lose the belief in people's freedom to make choices, and to overcome predispositions that might put them at risk. Yet if you believe that addiction is entirely dependent on life experiences, you can lose sight of many individual differences that can influence people's vulnerabilities to addictions including the potential that medications, such as antidepressants, can help address mental health problems that may contribute to addiction.