There is no simple answer to the questions, “What causes addiction?” and “How do addictions start?” Addictive behaviors involve a complex interaction of genetic and environmental factors that can vary across different individuals.

Addictive Behaviors and Genetic Factors

Research that examines the relationship between heredity (genetic factors) and addictive behavior typically uses family studies that can include investigations of addictive behaviors in parents and children, identical twins, fraternal twins,  adopted children, and siblings, to determine the genetic contribution to addictive behavior.

There have been numerous genes associated with addictive behaviors of all types as a result of the studies. However, not everyone who has a particular kind of addiction shares the same genes. Also, many people who share genes that are identified with addictive behaviors do not develop addictions.

There is no definite conclusion regarding the percentage of nearly any behavior that can be attributed to genetic factors. The best conclusion is that, like all behaviors, addictive behaviors share some genetic associations. Genes may account for some of the causes of addiction, but genes need to interact with environmental factors.

Risk Factors

Researchers and clinicians do not think of the relationship between genetics (heredity) and addictive behaviors as being causal. Instead, heredity (genetics) is considered to be a significant risk factor for the development of addictive behavior.

A risk factor represents some condition or situation that can increase the probability that someone may develop some type of trait, disorder, or disease. Risk factors are not considered to be direct causes; they only increase the probability (risk) that one might develop a particular condition.

Heredity is a known risk factor in the development of addictive behavior. The children of people who have been diagnosed with a substance use disorder are far more likely to develop one themselves than children born to parents who have no history of substance abuse.

However, not every child born to parents with a history of substance abuse will develop an addiction, and many children who have parents who did not abuse substances develop substance use disorders.

Even in identical twins who share 100 percent of their genetic material, one twin may have a substance use disorder, and the other twin will not.

When averaging the research studies, it appears that if one identical twin is diagnosed with a substance use disorder, there is about a 50 percent chance that the other twin will also be diagnosed with one.

Other Risk Factors

The other important thing to understand about the relationship between heredity and behavior is that a person’s genes cannot act in isolation.

For your genes to express themselves as behaviors, they must have some type of environmental stimulation. Thus, it would be grossly incorrect to state that your substance use disorder was caused by your genetic makeup.

The American Psychiatric Association (APA) has listed some of the more prevalent risk factors that are associated with the development of different types of addictive behaviors. These include:

  • Having a family history of a substance use disorder. This is most often considered to reflect a genetic predisposition, but it may also indicate a learning component to behavior.
  • Diagnosed with some other mental health disorder
  • Having a lack of family involvement
  • Using drugs or alcohol at an early age
  • Having peers who abuse drugs or alcohol
  • Having a history of significant stress or trauma, especially in childhood
  • Using drugs that are considered to be highly addictive, such as opioids or cocaine

Protective Factors

While much of the early research regarding the causes of addictive behaviors focused on risk factors, some of the more recent research has looked at factors that can shield or protect someone from developing an addiction.

It stands to reason that if genetics (heredity) can be a significant risk factor for the development of addictive behaviors, there must also be a genetic component that is associated with being relatively resistant to developing addictive behaviors.

If there are environmental risk factors that can increase the probability of developing an addiction, it stands to reason that there must also be environmental factors that can make one more resistant to developing addictive behaviors. These factors are typically referred to as protective factors.

Some protective factors include:

  • A supportive environment
  • Having significant outlets for stress
  • Learning to express oneself in a positive manner
  • Positive self-esteem
  • Good coping skills
  • Genetic associations

For instance, healthy afterschool activities for children have been demonstrated to reduce vulnerability to addiction. Even access to exercise can discourage drug-seeking behavior.

We all have certain psychological and biological characteristics and experiences that can make us more vulnerable or resistant to developing a substance use disorder.

Every one of these biological, psychological, and experiential risk factors and protective factors will exist through multiple different levels. These factors influence one another.

  • Personal relationships: Risk factors associated with personal relationships include parents who use alcohol or drugs, one or both parents being diagnosed with a mental illness, a parent who is abusive, or parents who provide inadequate care or supervision. A very strong protective factor against the development of addictive behavior in this context is solid parental involvement as a child and adolescent.
  • Community: Within the community, risk factors for substance abuse include living in a neighborhood where there is substantial violence or low socioeconomic status. Protective factors within the community include access to positive afterschool activities and faith-based activities.
  • Society: At the broadest level, the societal level, risk factors for substance abuse can include a poor economy, racism, and even laws and norms that are favorable to using drugs or alcohol. Protective factors would include legislation limiting the availability of addictive drugs and policies that discourage discrimination and hate crimes.

Factors that lead to an increased risk of developing addictive behavior are multifaceted, interact over numerous contexts, and will vary significantly from person to person.

Revisiting Heredity

Two attributes that are commonly associated with a significantly increased risk to develop some type of addictive behavior are impulsivity and sensation seeking. As it turns out, both of these attributes are also considered to have a high genetic component to their manifestation in individuals.

There are very few treatments that are designed to address these issues in people with substance use disorders. One of the treatments is a therapeutic technique known as contingency management.

In this technique, positive reinforcements for not acting impulsively are used to change impulsive behaviors.

Even though these qualities are considered to have high hereditary components, the most effective treatments are designed to change environmental conditions. This highlights the idea that heredity and environmental experience cannot be separated.

Genes and Choice

  • Impulsivity — a characteristic that is considered to have a strong genetic component to it — is also associated with an increased risk of developing an addiction.
  • The treatment for impulsivity in those who abuse substances is to use contingency management, a behavioral therapy technique that does not directly alter genes but may alter gene expression through a person’s choices and actions.
  • Even if you have a genetic profile that puts you at a high risk to develop an addiction, you have the choice of choosing addiction or not.


Although it is clear that genetics plays a part in the possibility of developing addictive behaviors, they are not causes of addiction. Even if you have a family history of addiction, you are not destined to struggle with addiction. The development of a substance use disorder is a result of complex, numerous factors.

The treatment of substance use disorders focuses on altering environmental factors and changing beliefs and attitudes. People who have significant protective factors may also have significant resilience to the development of an addiction. Some protective factors, like strong levels of positive social support, can be developed by altering a person’s environment.

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