Nature or Nurture: What Causes Drug Addiction?

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Peace Valley Recovery is located in Bucks County, Pennsylvania. Our mission is to provide patient-centered care that focuses on healing and recovery from addiction. This blog provides information, news, and uplifting content to help people in their recovery journey.

Authored by Elliott Redwine, | Medically Reviewed by Peace Valley Recovery Editorial Staff,
Last Updated: March 5, 2023

“What causes drug addiction?”

It’s a question that’s been around for as long as people have dealt with substance and alcohol abuse. Why do some individuals struggle to control their use while so many others can take it or leave it? Is it nature or nurture? What is it that makes some turn to drugs and alcohol?

Ultimately there is no single catch-all answer to this question. Addiction and alcoholism are complex conditions which means there are complex causes. It isn’t as simple as pointing at one particular thing as the source of substance and alcohol abuse.

Everyone has a different situation that led up to where they are. What causes drug addiction in an individual is often as unique as the individual. Are there times where one aspect plays a bigger role in someone developing a drug or alcohol problem, though? Can you look at nature vs. nurture on a case-by-case basis?

Determining What Causes Drug Addiction:
The Nature vs. Nurture Argument

Figuring out what causes drug addiction and alcoholism isn’t as simple as looking at a person’s family history. You can’t just point to the environment they grew up in or the friends they hung out with. Alcoholism and drug addiction are too complex a condition to point at a solitary cause.

There are two main causes of addiction and alcoholism: biology (or genetics) and environmental factors. Current research estimates that these two aspects share roughly a 50-50 split of what causes drug addiction. The precise ratios shift depending on each person’s specific situation, though.

For example, some people have little to no addiction or alcoholism in their direct family line but still develop a substance or alcohol use disorder. In cases like these, their environment is the majority cause of their condition.

Development, or the age when a person starts drinking or using drugs, also plays a role in the development of substance and alcohol use disorders. It isn’t necessarily a direct cause but does affect their mental and physical development if they start early enough.

Drug Addiction in Pennsylvania

How can each of these factors affect whether someone ends up with an alcohol or substance use disorder? What role do they play? Is there anything a person can do to avoid ending up with a drug and alcohol problem or is it inevitable that a condition will develop?

Biology (Genetics)

Oftentimes the first reaction when dealing with someone who has a drug or alcohol problem is to look at their parents. Does their mother or father struggle with their substance or alcohol use? It seems logical to look first toward their parents since genetics play a major role in most aspects of life.

But current research indicates that genetics play about 50 to 60 percent of the role in someone’s risk of developing a problem with drugs or alcohol. Many large-scale studies on twins show that genetics do play an important role even though they’re only credited for about half of the problem.

Numerous genetic components may increase a person’s risk, including metabolic processes and personality traits. One of the most important components to look for when determining what causes drug addiction or alcoholism is a preexisting mental illness.

Mental Illness

People with mental illness are more likely to turn to drugs and alcohol than those without. It isn’t easy to live with the symptoms of mental illness. Greater difficulties arise when their symptoms go undiagnosed or untreated for months or years.

While mental illness is not necessarily what causes drug addiction or alcoholism, it does increase a person’s risk. Some use alcohol and drugs to self-medicate and relieve the effects of their symptoms. They may fall into a pattern of consistent drug or alcohol use because it helps their symptoms in the short-term, but it makes them worse over time.

The presence of both a mental disorder and a substance or alcohol use disorder is called dual diagnosis or co-occurring disorders. Dual diagnosis is another complicated condition because of the way the symptoms of both disorders exacerbate each other. People with co-occurring disorders benefit from specialized treatment that considers how these conditions interact.


When determining what causes drug addiction, the environment someone grows up in or currently lives in is responsible for the other half of the equation. After looking at a person’s parents, the next instinct is to look at the environment they grew up in. What was their household like? Where did they live? Who did they spend their free time with? How did their role models behave?

Just like genetics, numerous environmental aspects contribute to what causes drug addiction and alcoholism. These factors include things like family, friends, exposure to or experiencing trauma, or economic status.


Children who grow up in a home with someone who has an active substance or alcohol use problem are more at risk. Whether it’s a parent, sibling, or another family member, early exposure to substances plant ideas in a child’s mind. Young children look for role models and if someone in their home uses drugs or alcohol they are more likely to do the same.