Episode 8

  • What role is played by genetics in addiction?

  • What makes one person become addicted  to drugs and alcohol and another person doesn’t?

  • Is environment more important than genetics?

There are many factors that influence the development of an addiction. There are complex risk factors at play for each person. Genetics are a big deal, but the risk is more than just our biology. This episode focuses on what increases the risk of developing an addiction.


In this Podcast 

  • Genetics account for at least half (50%) if not more of the risk in developing an addiction
  • The closer a person is related to addicted relatives the greater the risk
  • There isn’t one single gene responsible for addiction. Instead, its a combination of multiple gene variances
  • Environment is more active as a risk factor in adolescence and later in early adulthood on up, genetics are more active in terms of risk.
  • Mental health issues contribute to the risk of addiction.
  • Environment (using peer group, parental/familial attitudes about substance use) do have an impact on risk.


Helpful Links:


Chapter 2 The Neurobiology of Substance Use, Misuse, and Addiction, The Surgeon General’s Report on Alcohol, Drugs, and Health  https://addiction.surgeongeneral.gov/sites/default/files/chapter-2-neurobiology.pdf

The Genetics of Addiction https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4101188/

Genetics and Epigenetics of Addiction DrugFacts | National Institute on Drug Abuse (NIDA)  https://www.drugabuse.gov/publications/drugfacts/genetics-epigenetics-addiction

Genes matter in addiction https://www.apa.org/monitor/2008/06/genes-addict

The Genetics of Addiction: Where Do We Go From Here?: Journal of Studies on Alcohol and Drugs: Vol 77, No 5  https://www.jsad.com/doi/full/10.15288/jsad.2016.77.673

Genes and Addiction  https://learn.genetics.utah.edu/content/addiction/genes/

The Science of Hazel Eyes https://blog.prepscholar.com/hazel-eyes-color

Free Treatment Planning Tool  www.betsybyler.com/treatmenttool


You’re listening to the All Things Substance podcast, the place for therapists to hear about substance abuse from a mental health perspective. I’m your host, Betsy Byler, and I’m a licensed therapist, clinical supervisor, and a substance abuse counselor. It is my mission to help my fellow therapists gain the skills and confidence needed to add substance use to their scope of practice. 

I take topics that are typically aimed at substance abuse counselors and share them with mental health therapists in a way that is relevant and tailored to meet our needs. By adding substance abuse to your scope, you can expand your ability to treat the whole person and better meet your client’s needs. Bringing more hope, healing and freedom to the people you serve.

Doing therapy is hard work. Made harder when addiction is thrown into the mix. Many of us didn’t get the training we needed to deal with substance use and finding the knowledge that you need to fill that gap can be difficult. Each episode, I’ll bring you information on substance abuse, topics that impact our work, helping you gain knowledge and confidence. In a relatable and practical way. So join me each week as we talk about All Things Substance.

So last week we covered the neuroadaptations in the brain of an addicted person. We saw how the cycle of use digs the hole deeper and deeper. How the basic survival systems in the brain are hijacked by addiction. And the very thing that’s supposed to keep us alive ends up driving us towards death. 

I made the case that addiction is not a choice. If you missed that podcast, you can head on over to betsybyler.com/podcast and check out episode six and seven. We’re going to talk about why one person becomes addicted and another person doesn’t. It’s not personal fortitude or willpower. It is complex and multifaceted. We’ll cover risk factors in this podcast. And in the next one, we’ll talk about protective factors.

As therapists., our desire is to move our clients towards health and wholeness and addiction gets in the way of our client’s road towards the life they want. I believe that the better understanding that we have of addiction, the better our work will be able to be. This topic can sometimes be pretty heavy. And,  I’m hopeful that the information that you hear will be useful to you and ultimately useful to your clients

When talking about addiction, the age old debate about nature or nurture is relevant. The truth about addiction is that it’s both.  It’s nature and nurture. We’ll start with nature. Genetics.  This will be a brief overview. Genetics is incredibly complex and there’s a vast amount of information. New studies are coming out all the time and even more studies are ongoing.

Genetics are responsible for a large part of why specific people become addicted to substances and others don’t.  Addictions are moderately to highly heritable.  Studies done on families adoption and twins reveal that an individual’s risk tends to be proportional to the degree of genetic relationship  to an addicted relative.  The estimates vary from genetics being about 50 to 70% of the risk for someone who has a substance use disorder. The most commonly cited percentage is that genetics are responsible for half or 50% of the risk. 

The “how” of how this plays out is pretty complex.  Contrary to a lot of popular beliefs there is no one addiction gene. It was a commonly held belief that we would find the gene that predisposes someone to addiction and the research found  that there are many different gene variations that are present in those who suffer with addiction. It would be far simpler if we were able to isolate the genes responsible, but there are just too many. For reference,  the human genome project estimates that humans have between 20 and 25,000 genes. Every person has two copies of each gene, one inherited from each parent.

Humans are called diploid organisms because they have two alleles at each genetic locus with one allele inherited from each parent. Each pair of alleles represents the genotype of a specific gene. Let’s take eye color for instance. In a really simplified version of this, you get one allele from each parent.  And the combination of those alleles provides your eye color.  

One of my parents had hazel eyes and the other had blue eyes. I have blue eyes.  So we know that blue eyes are recessive, meaning that they show up least often. Blue eyes are often written as two small “b’s” when talking about genetics. So I got one small “b” from each parent.  My mom had blue eyes also  and so she gave me a small b.  She didn’t have another allele to give me. My dad had a small “b” too, but he also had another allele.  It was chance that gave me blue eyes. My sister got my dad’s other allele and she has hazel eyes.

Each of the estimated 20 to 25,000 genes have two alleles each . The reason this matters is that the genetics involved in addiction are happening on multiple genes. and we’ve likely not even found them all. The variations are one allele  apart. It’s called polygenic inheritance. The dominant capital genes are additive. The more genes impacted the greater the risk. In short, the more genes you have affected where you have a different allele that’s been activated the greater your chance of becoming an addict or an alcoholic. So why does one sibling like the feeling of being high or drunk to the point that they keep using more and more and another sibling with the same two parents doesn’t like it at all so they rarely do it?

Our example of eye color  is really simplified. In reality, estimates put eye color expression having potentially 16 genes involved. If eye color has several genes involved, how much more would contribute to addiction potential?  We can guess at risk, but we can’t isolate  and give a specific percentage of risk. 

Another component of the genetic discussion is the addiction risk factor that lies in the type of substance, a person chooses. The interplay between the type of substance used and the person’s body functioning, which is also determined by genes, impacts the risk of becoming addicted.

Each substance has unique features. They each have unique effects in terms of the high or intoxicated effect. They have unique characteristics depending on the amount used and each has a unique recovery or withdrawal impact. A vulnerable person may have a high preference for a particular substance or experience extreme withdrawal symptoms if they try to quit. On the other hand,  if a person is less vulnerable, they may feel no pleasure from a drug that makes others euphoric.

Let’s take a pair of siblings. Sibling A and sibling B.  Sibling A has variations on a few alleles that make a great difference in the way they experience substance use. Sibling A experiences less  hangover effects from alcohol than sibling B.  Sibling A has a higher tolerance than sibling B to start out with. Sibling A has an impact in the amount of novelty seeking that they do on a given day or in a given situation. Sibling B tends to be more cautious and reserved.  This is just a few characteristics  that wouldn’t be noticeable by people who didn’t know them. Both had the same upbringing, the same parents, the relatively same experiences while they were in school. And yet one has a much higher risk factor for becoming an addict or an alcoholic than the other.

Now, remember, risk is not fate. Risk is just that; it’s risk.  Just like a risk for breast cancer or risk for diabetes or  any other illness that tends to be hereditary.  There just aren’t specific markers that we can do a genetic test and find out. Now, of course there are a number of genes that have been specifically identified. 

We know  that they just finished mapping the human genome in our lifetime.  The human genome project began in 1990 and ended in 2003.  It might feel like we should know way more about genetics than we currently do . It took that long just to map all the genes in a human genome let alone all the different gene variances and what happens to each one of them in a given person.

Additionally, We might know what genes and their allele pairs do, but what about when they’re combined with this gene or that gene. All of that represents a level of complexity that we just don’t have the ability to understand right now.  The closer a person is to an addicted relative and the number of addicted relatives,  meaning the prevalence of addiction in the family,  increases the risk.  Some people have suggested that having two parents that have addiction on their sides increases your risk by 60%.

Another thing that genes do is influence the number and types of receptors in people’s brains which impacts how quickly their bodies metabolize drugs, how well they’re going to respond to different medications. For example, Naproxen sodium works best for my headaches, but another person gets more relief from ibuprofen. Genetics are responsible for why I can take pretty much any medication and have no side effects. And another person is extremely sensitive to medications. Even within biologically related siblings, there can be a vast difference in reaction to substances, foods, and environmental cues.

Certain drugs also have a higher rate of addiction than others. Not to say that you can’t get addicted to the other drugs. It’s just that it might not happen quite as quickly. It was found that drugs such as stimulants, cocaine or opioid painkillers may result in faster development of addiction than other drugs. 

Smoking or injecting drugs can increase the potential for addiction as well. How someone uses a drug isn’t just a personal choice. It’s an indicator of their use progression. We’re going to cover the route of administration in another podcast. For now though, what matters here is that people who are smoking or injecting drugs have a higher risk of becoming addicted. 

What I’ve found with the type of substance people choose is that  anxious people tend to use depressants. The idea of taking something to amp them up is just out of the question. They are already amped up and the idea of making that worst isn’t appealing. People who struggle with depression, tend to use things that give them energy. This mostly means stimulants, but some people have a paradoxical response to certain depressants and stimulants for that matter. Then there’s a third group of people  who use in what I call a “kitchen sink” method.  They don’t care as long as it works to distract them from whatever’s happening in their reality.

So we talked about genetics being 50% of the risk. And the other half of that are a number of other factors. One of which are mental health disorders. People suffering with addiction frequently present with comorbid conditions. Estimates of people with at least one substance use disorder and one mental health related diagnosis range from 45 to 60% of all of those who present with substance use. Personally, this seems pretty low to me, but that’s just an opinion.

There’s a ton of research about co occurring disorders, far too much to go through here.  But I’ll give two examples. There’s research that has found a correlation between alcohol use disorders and PTSD. It was found that alcohol use might increase the risk for PTSD by reducing the brain’s ability to recover from a traumatic experience.

If you recall, from last week, we talked about how the extended amygdala reduces the brain’s ability to manage stress and increases their sensitivity to it. And so if this is present and that person goes through a traumatic experience, it could very well impair their ability to recover naturally placing them at risk for PTSD.

The second example, the research shows a potential link between the use of high concentration THC and the onset of schizophrenia. For reference, high concentration. THC is anything over 10%. The way you get over 10% THC is by using edibles, dabs or wax, or using a THC oil for use in vaping. When you smoke the plant, it typically isn’t going to be over 10% THC. 

This is not to say that THC causes schizophrenia. What the research is suggesting is that if you have the specific genetic marker  that using high concentration THC could push it forward. Research goes on to suggest that it’s not just schizophrenia, but psychosis in general that can get pushed forward by use of THC. 

This is a really big deal for us. A lot of times, I think that therapists feel like smoking weed isn’t that big a deal because frankly it’s not as dangerous as some of the other things. And that’s absolutely true. However, if we have a person who is at risk for developing psychosis, so someone in their late teens through their twenties, we need to be aware if they’re smoking marijuana and we need to know if there’s genetic risk. We know that psychosis and schizophrenia aren’t totally genetically determined. It’s genetically determined only in about 50% of the cases. At least that’s what they found through twin studies  and those numbers could have shifted over time since those studies were done.

I recall sitting in a staff meeting probably 10 years ago  where a colleague was presenting a case where a young man was developing psychosis.  As the  discussion went on I asked if this person was smoking marijuana and the therapist looked at me and was like, “yeah”, as though it was totally irrelevant. Well, our consulting psychologist at the time  pointed out the research that correlates THC use with developing psychosis and this therapist just didn’t know that.

And that’s kind of the point. A lot of us didn’t get any kind of training in learning these different kinds of things. So if your client is smoking marijuana and you’re worried about psychosis, this is a discussion that you need to have because once someone flips that psychosis switch, it doesn’t go backwards.  It is possible that psychosis could dissipate when they stop using,  but that isn’t a guarantee. And the longer that it’s present, the risk is going to go up, that it sticks around.

Research has also found a link between ADHD and substance use disorders. They believe that having ADHD puts you at higher risk for a substance use disorder  due to impulsivity being increased, novelty, seeking being increased, lack of forethought about consequences among other things.  if you’re a person who works with kids and specifically kids who have ADHD, and a genetic risk factor for addiction. This bears watching because it places them at higher risk. And as we said before, these risk factors are additive.

Other reasons for the prevalence of co-occurring disorders are well known to us.  Our mental health clients are suffering with the effects of depression, anxiety, stress, trauma. And while we do what we can for some people, it’s not enough to keep them stable throughout the week and they find that substances may help alleviate symptoms. The relief or distraction from these symptoms outweighs the potential consequences at times.

I had a client come see me right after she saw our psychiatric nurse practitioner.  She had some pretty debilitating anxiety and was experiencing panic whenever in a public place. 

The nurse practitioner gave her a prescription for a medication. And told her to come back in six to eight weeks, pretty standard practice, and this nurse practitioner was really good. She sat in my office and said, “You know what? Six to eight weeks it might work in a book, but it doesn’t work in real life”.

Many of us know the struggle of having to get our clients to trust in the process and give the meds time to work.   I know I have been sitting there silently begging the Zoloft or the Prozac or whatever, to work faster, to give my client relief so that would give them some hope that they can feel better. 

Many of us have to work with our clients to accept that their mental health issue is a) real b)biologically based and c)that in many cases, medication could help. Then they have to wait weeks to see if the medication will even work and all that time they have 167 hours a week where they don’t see us and we’re not there to support them. Substances are available all the time and for people who struggle already with substance use, this can be a really difficult combination.

So we’ve covered risk factors as it relates to nature.   We talked about genetic risk from family members. We talked about the type of substance use  and how genes determine how those substances play out in a person’s biochemistry. We talked about mental health disorders and how certain mental health disorders impact a person’s likelyness to use substances and impact the effect of the use and how it interplays with their mental health disorder.  We also talked about our clients using substances in order to alleviate symptoms of their mental health disorder. and how sometimes they’re willing to trade one set of issues for another, because they’re better able to put up with the predictable symptoms of drug use and withdrawal rather than the unpredictable symptoms of their depression, anxiety, or PTSD.

So now we’ll look at risk factors related to nurture. If you Google risk factors for addiction, there are a lot of different lists. We’re looking at what is the highest level of risk factor rather than every single risk factor that exists? 

One common factor that shows up is how early the person starts using has an impact on their use. It’s labeled ‘early use’. And so the idea is that the earlier a person uses the higher their risk level.  The research supports this and it is backed up by anecdotal evidence.  In my own practice, I’ve seen this to be true. One of the things we ask people every time someone comes in, and we’re assessing their substance use,  is when was the first time you used substance A and substance B. And so on. 

There are likely a number of reasons for this such as becoming desensitized. Such as becoming desensitized to the forbiddenness of substance use, to wanting to increase the type of high they’re getting and changing substances. Harder drugs mean getting in touch with people who have them and who are farther into the drug culture than a young person would typically be.

The interplay between nature and nurture here has research as well. What they found is that early use is more impacted by environmental concerns and that genetics don’t really come into play until later.  When someone’s using during their development from early adolescence into later  adolescence  environmental and peer factors are really more important and things that are contributing more to use, whereas later on, genetics are really the factor. Which makes sense if you think about how the progression works. 

Early on, people are using around their friends; they’re experimenting and it’s not really turning into a problem yet.  The idea that you become addicted instantly doesn’t hold up to scrutiny.  And by the time they’re getting out of high school, their genetics are kicking in  and making their use increase greatly. And so that even if their peers aren’t using as much as them, they will transfer to a group of peers who are.

The Virginia twin study revealed that in early adolescence, the initiation of use of nicotine, alcohol and cannabis are more strongly determined by familial and social factors. But these gradually decline in importance during the progression to young and middle adulthood when the effects of genetic factors are at their highest.

Early prevention is super important.  Each year that we can push off the first use of substances, the better.  Other risk factors, poor family cohesiveness, low parental monitoring and involvement and parental substance use or attitudes about substance use are huge risk factors as well for early substance use.

The risk factor of having using peers is one that we’re all really familiar with. Not just true and adolescence early adulthood. But I’ve also seen this in adultier adults. They often struggle with the idea of how others will view their sobriety or how they will lose friends if they don’t use whatever substance.  It’s not surprising because we are built for connection  and by the time addiction is setting in the person’s peer group will be mostly, if not all, other people that use.  People don’t want to be high or drunk around sober people. It’s not fun. And it tends to make people have to think about their own use. And when you’re using  you definitely don’t want that kind of buzzkill.

So during part of my career, I ran an adolescent substance use group. The kids were either in the dependent stage or pretty close to it. So these aren’t kids that were just experimenting. These were kids who are using at least multiple times a week, if not daily.

I was at the part of the group where we talk about genograms and I would ask for a volunteer.   I would draw a genogram  on the big whiteboard.  He was 18, although still high school age, he volunteered to have his family drawn on the genogram. I knew him fairly well. I knew that he would be okay with it.

So I asked him about him, his siblings, his parents, his grandparents, and his aunts and uncles.  Once we had all the family members on the board, I also added his girlfriend and their child to be. They were having a daughter in approximately four months from the time that we did this genogram.

So I asked him a number of different things and asked him to identify who on the genogram experienced these things.  I used different colors to outline around each person. 

So I used a number of different factors, physical and medical illnesses (such as diabetes or cancer), mental health issues (such as diagnosed depression, anxiety, PTSD, schizophrenia, those kinds of things), anger and violence,  experience in prisons and jails and finally substance use. Defined that substance use wasn’t someone who was drinking normally or using normally, but someone who had problematic use. 

As we sat back and looked at the genogram,  nearly every single relative had every single thing circled. So each person had a green line around them and a brown line and a red line and a purple line. All of the factors. The only thing that wasn’t super common was the physical stuff. And then we got down to our identified person who was their group member and he had every one of them except for the physical stuff yet.

And they kind of sat there and it was silent for a minute. I know that part of them were thinking, wow, that’s a lot. And another part of them was visually mapping out their own risk in their head. And so we talked a little bit about why he got into using,  how early it was, what changed, what was going on with his parents, witnessing domestic violence, growing up experiencing physical abuse from his dad,  having both parents be alcoholics, every family gathering everyone’s hammered because the aunts and the uncles and the cousins and everybody’s drinking. What chance did this kid have of coming out of that?

I asked him to tell me about the girlfriend. So I started drawing lines around her circle. She struggles with mental health.  She struggles with depression, anxiety, PTSD.  She uses substances.  She gets really angry and dysregulated and can get violent with him. And then I turned to the group  and pointed to the baby’s circle. And I asked them, tell me what her risk is. And the group went pin drop silent. And one of the kids said, “that’s not fair”. And I said, “what’s not fair?”  And he said “That’s not fair that that kid has all that  just coming into the world”.

And my response was “No, it’s not fair. And remember, it’s  risk, not fate. What does he need to do as her dad to make sure that it doesn’t become a reality”. And I’ll tell you what those kids knew. They knew what he needed to do as this girl’s dad, to make sure that she had every chance. Because they were listing all sorts of things that they didn’t get that they needed. And it  just so happens that all of those things were directly in line with what the research tells us are protective factors when talking about substance use. That’s going to be the topic of our next episode. And I’ll finish the story and the things that they said would have helped them and the things that they needed that they didn’t get.

I’ll see you next week. When we talk about protective factors.

If you’re ready to take the next step in addressing your client’s substance use head on over to betsybyler.com/treatment tool. The treatment planning tool I created will help walk you through the process of evaluating your clients use and deciding how and when to intervene. The tool is completely free and will be delivered to your email so that you can use it right away.

Thank you for listening to the All Things Substance podcast. For show notes, links and downloads, please visit betsybyler.com/podcast. If you loved what you heard today, it’d be great if you would share those with your therapist, friends, and colleagues. If there are topics that you think would be useful and you’d like to hear me cover them, please let me know. Just send a message to podcast@betsybyler.com. I’ll see you on next week’s podcast and until then have a great week.

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