Genetic Influence on Substance Abuse

There have been several research studies that indicate that there are genetic factors that increase a person’s predisposition for drug and alcohol abuse addiction. Finally, there is some substantiated evidence that drug abuse and alcoholism run in families, confirming a suspicion that has been speculated on for years. According to recent research, about 50 percent or more of addiction problems are linked to genetics. Studies on twins and siblings have been used to identify high-risk genes that are likely to play a role in addiction. Unfortunately, isolating the gene culprits is not easy since there is no one gene to blame. There are also environmental links that must be considered.

Twin Study Research

Medical researchers use twin studies to answer questions that are related to the “nature versus nurture” debate. Given the many environmental issues that can be tied to drug and alcohol addiction, twin research has been used to try and understand the impact of both genetic and environmental forces. According to the paper published by Danielle M. Dick, PH.D. and Arpana Agrawal, PH. D. entitled “The Genetics of Alcohol and Other Drug Dependence,” both twin and adoption studies reflect a significant link between genetic factors and alcohol and drug addiction. For more detailed information, see the full report at this link.

Findings from twin studies found a correlation between alcohol and drug dependency between identical twins that by definition share 100 percent of their DNA.

When identical twins were compared to fraternal twins that share only 50 percent of their DNA, identical twins were more likely to share an alcohol addiction or alcohol dependency. This result indicates that shared genes increase the probability of addiction. For more detailed information, review this report.

When data was analyzed from the Virginia Twin Registry, research scientists found a common genetic pattern that manifests in different ways including alcohol and drug addiction and other antisocial behavior. The same patterns were documented in other twin studies, providing even more proof of these genetic links to an increased predisposition to addiction. The genes identified are responsible for the way specific drugs are metabolized in the body.

Genes Linked to Addiction

Based on the findings that indicate there are genetic contributors to alcohol and drug addiction, scientists are busy now trying to determine which genes are responsible for this link. Unfortunately, there is not just one gene, but rather several suspected of being linked to alcohol and drug addiction. After major research that started in 1989, the Collaborative Study on the Genetics of Alcoholism, which examined families that had several family members addicted to alcohol from several U.S. sites, identified certain genes that appear to be linked to addiction problems. A thorough psychiatric interview of these families has elicited information about both alcohol dependence and drug addiction.

Findings that cannot be ignored based on consistent results pointing to alcohol dependence associate genes involved in the metabolism of alcohol. Genes encoding ADH1 and ADH1C have been isolated as alleles in laboratory experiments that have shown very high enzymatic activity. Genetic variants observed in ADH1A, ADH1C, ADH5, ADH1B, ADH6 and ADH7 are linked to drug dependence. Additionally, chromosome 4 contains gene clusters that appear to be linked to drug abuse.


Given the amount of data that must be analyzed, scientists are still seeking answers. While certain genes apparently contribute to a predisposition for alcohol and drug addiction, scientists are not inferring that these gene combinations cause addiction. More twin and family research is needed. Ultimately, these studies will provide the information required to test for vulnerability to alcohol and drug addiction so that prevention measures can be taken to protect individuals the most susceptible to developing addiction problems in life.