Is Addiction Hereditary? Understanding The Genetics Of Addiction

Published on March 1, 2023

It is well-established that a family history of substance abuse influences the risk factors that contribute to addiction. However, until fairly recently, it was nearly impossible to determine whether that influence was actually genetic or simply environmental.

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In the field of neurobiology and the study of addiction, a decades-long debate formed over whether substance abuse was genetic or environmental.

As a result of continued research, we now know that addiction is between 50% and 70% heritable, depending on the substance. Of course, there is still much to learn.

Does Addiction Run In Families?

Addiction does run in families, but the exact reason for the familial link in cases of substance abuse is still imperfectly understood.

While we know that genetics play a significant role, this connection is not the result of a single genetic factor. Rather, there is a number of interlinking factors that contribute to addiction risk.

Genetic Factors

The genetic factors that contribute to a person’s risk of developing a substance abuse disorder are related to the reward center of the brain and how the person responds to dopamine.

In people who are at greater risk for substance abuse disorders, dopamine receptor expression is weaker, making them more sensitive to the rewarding effects of drug and alcohol use.

This variation in drug response affects:

initial sensitivity
tolerance
sensitization development

While this explanation for why some people are more likely to develop a substance use disorder is certainly useful, the genetic reason for this variation is complex and further research is needed.

Environmental Factors

Genetics clearly play a role in a person’s response to drugs and alcohol, but they do not account for 100% of addiction risk. Environmental factors are still vital to understanding addiction.

Factors like early exposure to addictive substances, adolescent trauma, dysfunctional family dynamics, and mental health disorders account for 30% to 50% of addiction risk.

These factors are largely responsible for the elevated addiction rates among LGBTQ+ people, veterans, and other high-risk groups.

Fortunately, state-provided addiction resources for veterans and other at-risk groups can help to reduce those rates.

Why Is The Heredity Of Addiction So Complex?

Despite decades of work on the subject, scientists are still piecing together the genetic factors that influence the likelihood that a person will develop a substance abuse disorder.

The work is incredibly complex and difficult to study because it is nearly impossible to separate genetic and environmental factors working with human subjects.

In an effort to continue improving our understanding of addiction and heredity, modern researchers rely on studies of animals raised in a controlled setting and human, identical twins.

Through these efforts, scientists are able to parse out some of the complexities that affect our understanding of addiction risk.

Hidden Genetics

Genetic factors that contribute to addiction can be difficult to study, as many people who are conceivably at an increased risk for substance use disorders have never developed one.

Brain Outcomes

Addiction causes physical and chemical changes in the brain that further complicate research, as it is not always possible to know whether a variation pre-exists addiction or is a result of it.

Epigenetics

As living organisms develop and engage in new experiences, these can actively affect gene expression, further complicating scientists’ ability to study inherited traits.

Together these factors influence:

brain development
personality comorbidities
stress-sensitivity resiliency
pleasure aversion
neuroplasticity
pharmacogenomics

All of these muddy the waters, making it difficult for scientists to identify the precise inherited traits that contribute to a person’s risk of developing an addiction.

What Substance Use Disorders Are Most Closely Linked To Genetic Factors?

Based on the current data, there is some variation in the extent to which genetics affect the risk for specific types of substance abuse.

Alcohol Addiction

Genetic factors appear to account for about 50% of a person’s risk of developing alcohol addiction. Cultural tendencies toward alcohol abuse also play a significant role.

Tobacco Use

Genetics account for approximately 75% of a person’s inclination to smoke and about 60% of their risk of nicotine addiction.

Stimulant Abuse

Addiction to stimulants like cocaine and amphetamines is up to 70% heritable.

In fact, researchers found that variations in the D2 receptor gene were more pronounced in white subjects who engaged in polysubstance abuse, especially those who preferred stimulant drugs.

Opioid Addiction

Heroin abuse and other forms of opioid addiction are also up to 70% heritable. The over-prescription of addictive opioids is a major contributing factor.