Substance abuse and addiction affect over 23.5 million people in the United States. With over 10% of the U.S. population estimated to suffer from a substance use disorder at some point in their lives, one in five Americans is affected, because their friends and family members are addicted. Addiction is a complex and multifaceted disorder, with science showing an increasing link to genetics, environment, and nurturing. For example, it is widely recognized that many people can use certain substances such as cigarettes relatively safely and about 10-15% of the population will very quickly become addicted instead. Are genetics to blame for these “addictive” personalities. Does addiction run in families because of genes? Or do children of addicts often become addicts because they are exposed to substance abuse from an early age?
While research is showing an increasing link between addiction and genetics, the answers are very often not clear-cut and are often complex and intertwined. Today, we are more aware than ever that addiction is complex, nuanced, and personal. Genetics can often play a role but inheriting “addictive” genes” doesn’t make you an addict, instead, it increases susceptibility, with a wide range of contributing factors such as family, environment, and social life playing into the problem. This change in viewpoint is also changing how we view addiction treatment, so it is important to understand how and why genetic factors can have a role in addiction.
Is Addiction Heritable?
Most people look up addiction and genetics with a few simple questions in mind, largely related to “Is addiction heritable”. The answer is yes and no. It is very possible that you could inherit genes which would increase your susceptibility to addiction, your responses to certain substances, and your risk-seeking behavior. On the other hand, most people aren’t born addicted, and when they are, they are very quickly weaned off of the substance they are addicted to. It takes conscious choice and re-exposure to result in a new addiction.
However, genes which will contribute to susceptibility, or an increased risk of addiction, are very easily inherited through two separate factors – genes and epigenetics. How does that work?
Genes – Genes are the basic, functional unit of hereditary. They are passed down from parents to children, with dominant genes having a 50% chance of carrying through to the child, even if only one parent has the gene. Here, genes like BRCA1 are widely recognized for their genetic link to breast cancer. Most people would easily recognize that health problems including Alzheimer’s, balding, bipolar disorder, and even male pattern balding are all heritable. They’re also each heritable because of a gene linked to the physical problem. While many people are vehemently opposed to the “nature” part of “nature vs nurture” in addiction, genes can play a role in susceptibility to addiction. To date, we’ve identified over 900 900 individual genes relating to how the brain processes dopamine, serotonin, and opioids, which are extremely important in processing the risk of addiction.
Epigenetics – Epigenetics are heritable markers in DNA, composed of chromosomes and DNA which adapt based on experience. They are passed on for anywhere from 1-4 generations and serve the function of ensuring that children are adapted to their current environment. Epigenetics are well understood to impact how individuals process trauma, how they experience relationships, and even how they learn. They’re also increasingly being linked to susceptibility to addiction, as parents who drink or use drugs pass markers on that make their children more sensitive to substance use. Epigenetics serve very valuable functions in terms of preparing children for famine, stress, or another negative environment, but work against children whose parents, grandparents, or great grandparents were using, because it makes them more susceptible to substance abuse themselves.
The Three-Factor Model
While genetics are increasingly recognized as playing an important role in susceptibility to addiction, most research indicates that it is far from the only factor in play. Most researchers and physicians recognize the Three-Three-Factor model, which suggests that most addiction can be traced to three primary factors; genetics, nurture, and exposure.
Genetics – Genetics are thought to contribute to as much as a 40-60% increase in susceptibility to addiction for individuals with relevant genes. These genes affect risk-taking behavior (increasing the likelihood that individuals will take substances to begin with), will change the individual’s reaction to the substance, and change how the brain processes dopamine or other neurotransmitters, which increases vulnerability once drug or alcohol use begins. Genetics largely increase susceptibility to addiction. Epigenetics also play an important role, simply because the body becomes more tolerant of substances and reacts to them differently when exposed.
Nurture – The nature vs. nurture argument is a long and ongoing one, but evidence increasingly points to “Nature and Nurture”. Here, children who are raised in a traumatic environment are significantly more susceptible to substance abuse and addiction. The Adverse Childhood Adverse Childhood Experiences (Ace) study conducted in the 1990s studied over 17,000 participants, effectively linking poverty, poor family relationships, family substance abuse, accidents, stress, and physical, emotional, or sexual abuse to increased susceptibility to addiction. So, individuals raised around substance abuse, raised in unhealthy family relationships, or who otherwise experience significant stress or trauma are significantly more susceptible to substance abuse. Nurture also plays another role, in that children raised in poor households may simply develop unhealthy coping mechanisms. Poor parenting can result in bad habits and poor mental discipline, rebelliousness, and risk or pleasure-seeking coping mechanisms. This does increase the likelihood that an individual will use as a coping mechanism.
Exposure – No one becomes addicted without exposure. The act of actually using a substance is the single factor in all cases of addiction, and the most important one. Experience-dependent neural plasticity means that the brain cannot learn behavior unless it repeats that behavior, and it very much applies to addiction. This means that, in order to become addicted, a person must choose to take a substance and then continue to take it for an extended period of time. Addiction is a learned behavior.
So, Do People Inherit Addiction?
While there are certainly many heritable factors to addiction, none of those factors directly contribute to addiction. It is the act of physically taking a substance that directly contributes to addiction. Most importantly, hereditary susceptibility to addiction doesn’t mean you have to be addicted, it simply means that you are more likely to become addicted if you do use or drink. Even if you are highly susceptible to addiction, you can still get treatment, learn coping skills, learn stress management, and work to avoid or manage substances that will cause addiction.
Genetics do play a large role in susceptibility and vulnerability to addiction. However, you do have options, and even if you’re already addicted, you can get help. Many people with both nature and nurture factors influencing susceptibility to addiction go on to lead healthy lives without drugs or alcohol. They are simply more vulnerable to developing an addiction should they be exposed and choose to continue that exposure.
This means that if you or a loved one are addicted to a substance, you can get help. A modern drug rehab program will tackle every aspect of addiction with support for physical withdrawal and detox, counseling, group therapy and peer support, behavioral therapy, stress management, and learning coping skills to guide you through learning how to be happy without drugs or alcohol.
While genetic factors can greatly increase the risk of addiction, it doesn’t mean you have to be. There is help. Just make sure that you take your history, family history, and medical history to your treatment facility, so that they have all the tools to help you recover.
