The Fix asks the question quite bluntly: Is addiction genetic or not? While the question may be easy to ask, the answer is less straightforward. The ambiguity stems from a lack of understanding of what genes are, and what they do.
Genes are molecules that contain information about a particular human being. There are approximately 22,333 genes in the human body, although this count is likely to change as advances in genome mapping are made. The information determine visual characteristics, such as eye color, hair growth patterns, and skin color. The information could also determine whether a person is likely to develop a particular illness or genetic condition.
For example, if a gene cannot synthesize a key muscle protein, a person will develop muscular dystrophy. The National Human Genome Research Institute explains that many medical conditions have a genetic component, which means that a person is at risk for developing the condition if it runs in their family, but it does not determine if the person will actually develop the condition.
That difference is key to understanding the role of genetics in addiction, and whether addiction is a question of nature versus nurture – or, to put it a better way, how much of addiction is nature versus nurture.
In 2012, CNN published a list of five myths surrounding addiction. The first item on the list is the belief that genes simply “cause” addiction, which some people take to mean that if there is no history of alcoholism in their family, allows them to drink with impunity.
However, the fact that rampant alcohol abuse can cause liver disease (or outright liver failure), alcohol poisoning, and lead to dependence on and addiction to alcohol (among a host of other medical conditions) even among people who have no apparent genetic inclination toward such conditions, suggests that the liability of developing an alcohol-related substance abuse problem goes beyond family history.
According to the National Association for Children of Alcoholics, even though the children of alcoholic parents are four times more likely to grow up to become alcoholics themselves (compared to children who grew up with parents who didn’t abuse alcohol), the factors of whether a person will develop an addiction are a complex combination of environment, lifestyle, upbringing, mental health, demographics, and, fitting somewhere into that spectrum, genetics.
Writing in Psychology Today, a licensed therapist (and recovering addict) explains that the development of his habit was like a time bomb, just “waiting for the right configuration of events” to kick into a higher gear.
One such configuration is parenting. Even if both parents have alcoholism in their blood (as it were), the therapist writes that a strong upbringing can be a shield against the genetic inclination toward substance abuse. To that effect, the National Institute on Alcohol Abuse and Alcoholism identifies four styles of parenting that run the gamut of structure and discipline:
Research has indicated that children who are raised by parents adopting the authoritative model of parenting tend to be more successful than their peers, when measured for self-image, academic success, or substance abuse (or lack thereof). The key reason the authoritative style so effective is because children who grow up in that structure learn important approaches to problem-solving, and how to regulate and express their emotions, to where they can develop skills and strategies against the harmful thought patterns that often come before substance abuse. The support and discipline provided by authoritative parents foster healthy decision-making about making potentially harmful choices to healthy childhood development, like whether to drink before the child is emotionally and intellectually (not to mention biologically) ready. In this way, a nurturing environment could offset the nature of the genetic component of addiction.
Further to that point, the Proceedings of the National Academy of Sciences published the results of a study that looked at the use of marijuana among twins, and found that factors in childhood development may have a greater role in determining whether people who smoke cannabis will develop a dependence on it.
That said, to assume that the genetic side of the equation can be easily overlooked in favor of a solid upbringing would be a mistake. The Wall Street Journal writes of how male children of male alcoholics are nine times more likely to become drinkers themselves, when compared to the general population. Further research has indicated that babies of alcoholics, adopted into homes where there is no drinking, have the same risk of developing alcoholism as they would if they had stayed with their biological parents.
The American Psychological Association sums it up thusly: “Genes matter in addiction.” The National Institute of Alcohol Abuse and Alcoholism quotes research that indicates the risk of genes determining alcoholism is around 50-60 percent (while providing the caveat that “features in the environment” make up the other 40-50 percent.
The key word NIAA uses is “risk.” No one inherits an alcohol use disorder or a drug use disorder; they inherit the risk of developing such a disorder, and for some people, that risk could be as great as a 60 percent chance that one drink – a beer at a football game or a glass of wine at dinner – will be the “right configuration of events” the Psychology Today therapist spoke of as the trigger for the time bomb.
In “Genes and Addiction,” the University of Utah explains that there is no such thing as a born addict; or, put more clinically, the susceptibility of addiction does not mean that an addiction is inevitable. It does mean, however, that other (potential) triggers in the person’s life have to be examined more closely, to discern whether or not that person is likely to develop a substance use disorder.
One such trigger is mental health. The genes that play a role in the determination of mental health conditions work in a very similar way as the genes that are involved in determining the possibility of addiction. For example, certain mental health disorders (such as depression, anxiety, and stress) have all been associated with the development of substance abuse in an individual.
However, explaining the relationship between “major depression and genetics,” Stanford Medicine writes that “genes play a role in causing depression,” and not “genes cause depression” – in the same way that genes play a role in what leads to addiction, and not merely “genes lead to addiction.”
Similarly, Everyday Health explains that while genes account for the tendency to develop an anxiety disorder (the umbrella term for a variety of conditions, such as panic disorders, post-traumatic stress disorders, and obsessive-compulsive disorder), life experiences and environment can be what triggers the anxiety disorder to go into effect. Negative situations in everyday life, such as difficult family relationships, tension and stress at a job, and financial problems, can be what pushes the anxiety switch. Controlling for those – perhaps with exercise, yoga, meditation or prayer, and therapy – can balance out the genetic risk for anxiety disorders in much the same way that nurturing a healthy, positive attitude can balance out the risk for a natural inclination to drink or use drugs.
The journal of Biological Psychiatry writes that stress is a key trigger for abstinent smokers to relapse into their habits. A study on “genetic predisposition to stress sensitivity” published in the journal asked if a natural tendency toward low or high levels of stress has any connection to addiction-related behavior, specifically whether drug addiction could be triggered (or re-triggered) by stress. The researchers concluded that as far as nicotine was concerned, having the genes for stress sensitivity probably wouldn’t lead someone to smoking, but having those stress-related genes would make life difficult for someone who had quit smoking.
The overlap between mental health disorders and substance abuse, also known as a dual diagnosis, is explained by the National Institute on Drug Abuse in terms of genetics. It is possible that genetic variations can make a person at risk for both an addiction and a mental health condition, and it can make the person at risk for one condition developing after the first. In other words, while genes can account for up to 60 percent of the risk for addiction, genes that carry information that determines the chance of a mental health disorder may account for 40 percent. Combined, natural inclinations toward a substance use disorder may win out over all the positive nurturing that can be provided, and such inclinations can also work against any therapies that have been put in place after a first bout of substance abuse has been treated.
Nature and nurture have a very close relationship, but what if nurture corrupts nature? At the University of Texas at Austin, the Director of the Addiction Science Research and Education Center explains that people who are on the high end of the spectrum of genetic predisposition to substance abuse are at risk for what he calls “instant dependence” – the one drink at a ballgame or party that sets off the bomb. For them, the danger is far too great to flirt with, meaning that the safest way they can ensure never triggering their risk is to completely avoid alcohol (or drugs), and anything to do with consuming alcohol or drugs.
That accounts for nurturing, but what about someone who is not “genetically loaded” for that risk? There is a plethora of other reasons why someone may choose to drink excessively, even if they have no such genetic inclination towards doing so. Gradually, over time, that person’s brain adapts to the constant flow of alcohol, raising the tolerance ceiling higher and higher to the point where moderate or infrequent consumption fails
to have any effect. This process is called neuroadaptation, and it does not need a genetic marker to happen. It can, however, cause certain genes to become vulnerable, and these genes may be passed down to children., 
Neuroadaptation is not limited to alcohol. The Proceedings of the National Academy of Sciences journal found that chronic marijuana use also causes neuroadaptation, and the journal Addiction found that the risk of initiating marijuana use, and using marijuana to the point where it became a problem, were “significantly influenced” by genes (nature), and by sharing an environment with someone who smoked marijuana (nurture)., 
In this way, someone with no family history of substance abuse can (with the right combination of factors) create a genetic predisposition toward addiction, which in turn gives their offspring a 50-60 percent chance of developing a substance abuse problem themselves.
We know now that genetic risk for developing anything is not a “yes/no” switch, but even this is a fairly recent development in the study of genes and addiction. More discoveries are being made. In 2013, Nature Communications published the results of a study that located a gene that not only regulates alcohol consumption, but, when not working properly, “can cause excessive drinking.” Acknowledging that this is still not a final judgment in the examination of nature versus nurture, one of the lead scientists pointed out that the growing understanding of the complexities of alcoholism, and identifying key triggers – whether in DNA or in the environment – can go a long way in formulating more effective treatment programs for the future.
To that point, Pacific Standard points out that thinking of those struggling with addiction as patients who need treatment opens up a plethora of treatment options, models, and possibilities. Thinking of people who struggle with substance abuse issues as weak-willed, morally bankrupt individuals dismisses offhand any realistic, tangible, and scientific approach to combating addiction. Even for all the good Alcoholics Anonymous does, says Pacific Standard, the lack of any medical treatment the program offers harms the insistence that addiction is a (very complex) disease.
The fact that addiction is being discussed on the genetic level indicates the seismic degree to which the conversation has shifted. Historically, alcoholism was seen as a moral weakness, a failing on the part of the individual to rein in their temptation and vices. Before Bill W. and Dr. Bob came together to form Alcoholics Anonymous in the late 1930s, the common belief surrounding drinkers was that they were lazy sinners who were too weak to say “no” to the offer of a drink. 
It was AA that first started to use the word disease to describe alcoholism, although the concept took a while to catch on. Now, it is almost taken for granted. NPR juxtaposes how earnestly and universally the Republican candidates for the 2016 United States presidential election talk about addiction as a disease that needs treatment, compared to presidents from the 1980s and 1990s, who, riding on a wave of being tough on crime and launching the War on Drugs, spoke of addiction in terms of crime and punishment.
The evolution is best seen in the words (and even in the existence) of what NPR calls a “conservative justice reform project.” The policy director of NPR says that while accepting that the use of drugs is destructive, and programs should be in place to dissuade people from abusing substances, treating those addicted to drugs – not sentencing them to prison – is usually the solution.
Now that more is understood about the nature of drug abuse, and the role that environment and mental health play in it, authorities are less willing to arrest users en masse. In Gloucester, Massachusetts, a police chief has told his officers not to arrest heroin users, even if they are caught with drugs, and instead to walk them to the nearest treatment center. In Seattle, a new program gives officers the prerogative to accompany people arrested for minor drug offenses to meetings with social caseworkers instead of booking them into jail.
Even as more and more institutions look at substance abuse as an issue of health and disease (as far back as 2000, the Western Journal of Medicine unequivocally stated that “Addiction is a treatable disease, not a moral failing”), there still exists a widespread impression that people struggling with addiction make a conscious, knowing choice to consume drugs or alcohol. A 2014 poll of more than 700 people across the United States revealed that active drug users still face stigma from the general public, the latter of whom might oppose measures to provide insurance, housing, or employment to help people with drug addictions.
The study leader behind the poll posited that since most drug use is illegal, the prevailing – and historic – opinion is that those who engage in drug use are criminals and must be treated as such. Ironically, the poll’s respondents were much more amenable to issues of mental health, finding that people who suffered from mental health disorders were more deserving of services and resources for treatment and integration into society – even though mental health often influences substance abuse, and vice versa.
Drug addiction is an unfathomably complex process – one that can start well before pregnancy and continue long after the last drink is taken. Substance abuse is, understandably, a very sensitive topic for a lot of people, especially when the concept of family history is brought into the discussion. For many, the suggestion of a genetic role in addiction is a Pandora’s box; the fundamental misunderstanding of what that role means (and the importance that the role should not be over- or underestimated) contributes to the long-running debate on nature versus nurture in the science of addiction.