Decoding Alcoholism: Is It in Our DNA?

Alcohol use is deeply ingrained in society, and for many people, having a few beers after work or a glass of wine with dinner is no big deal. For others, it can become an addiction. In a 2020 national study, half of the population age 12 and older reported using alcohol within the last month, but only around 10% met the criteria for alcohol use disorder within the year.

This discrepancy between some people’s ability to drink alcohol without concern and those who develop a dependency on it opens up some interesting questions. What causes some people to develop a dependency? Does it run in families? If it’s genetic and you have no family members who struggle with alcohol use disorder, can you develop it, too?

There are no simple answers to questions about addiction and dependency. The long and short of it is that both genetic and environmental factors play a role in the development of alcohol use disorder.

Nature vs. Nurture: What Causes Alcohol Use Disorder?

Anecdotally, people may say that alcoholism runs in their family or refer to an “alcoholism gene” in their family’s history. While genetics play a part, they are only half the story. In fact, research shows that genetics determine about half the risk for the development of alcohol use disorder, with environmental factors accounting for the second half. In some cases, it’s the interplay between an increased genetic risk and the environment that triggers alcohol use disorder.

Twin studies provide insight into this interplay. While in most cases, twins will still share the same environment growing up, these studies reveal the genetic contribution to alcohol use disorder by comparing the difference between monozygotic (identical) and dizygotic (fraternal) twins. In studies, the concordance of alcohol dependence is higher in monozygotic twins, suggesting a genetic component since monozygotic twins share an identical genetic makeup. These studies suggest that between 40 and 60% of drinking habits and alcohol dependence can be linked to genetics.

Genes Affecting Alcohol Use Disorder

Studies surrounding alcohol use disorder reveal several genes associated with an increased risk of drinking too much and developing compulsive habits around alcohol. Several pairs of genes discovered to be linked to alcohol use disorder are also associated with other neuropsychiatric disorders, including schizophrenia, Parkinson’s disease, anxiety and bipolar disorder. These genes include:

• ADH1B: ADH1B is an interesting case in alcohol use disorder. It has a low prevalence in Caucasian populations but is highly prevalent in East Asians. This gene impacts the liver’s ability to metabolize alcohol. Variants of this gene can cause a flushing reaction to alcohol and increase the feeling of illness when consuming alcohol. It acts as a deterrent for alcohol use disorder, and populations who do not have this gene, such as those of European ancestry, have an increased risk of developing a dependency.
• GABRB1: Mutations of this gene change gamma-aminobutyric acid (GABA), a neurotransmitter that inhibits a nerve’s ability to send or receive messages. While it slows down the nervous system, it also produces a calming effect. Those with certain mutations in the GABRB1 gene may have less GABA in their brains than the average person when sober. Alcohol changes the amount of GABA available to the brain to induce the sedative effect, which can encourage people to drink more to feel better.
• Beta-Klotho: The beta-Klotho gene is associated with drinking less. Those with this gene appear to be better at controlling their alcohol consumption and usually stop after drinking one or two. Those without this gene are less likely to stop their alcohol consumption.