Addiction is a family disease because it affects everyone in the family system in which it occurs, but also because it runs in families. Addiction runs in families through genetic transmission. Most people who use alcohol or other drugs don’t become addicted. If you’re speaking with a group of addiction treatment patients or people in recovery and ask them to raise their hand if they have abiological relative—mother, father, grandparent, uncle, aunt, brother, orsister who struggled with addiction, you’ll see most every hand go up. NIDA-supported research has studied patterns of drug use inpairs of identical versus fraternal twins in order to clarify the roles and interrelationship of genetic and environmental risk factors in the development of drug use, abuse, and addiction. Researchers examined the patterns of marijuana and cocaine use by female twins and found that genetic factors play a major role in the progression from drug use to abuse and addiction. This research supported other studies that showed family and social environmental factors to be influential in determining whether an individual begins using drugs. The findings further indicated that the progression from the use to abuse or dependence was due largely to genetic factors (4,5,6). Although it’s not the case that someone has to have a family history of addiction in order to become addicted, the reality is that genetics play a significant role in the development of addiction. what seems to be the science behind the statistics is that people inherit a biological vulnerability to addiction. It’s called biological vulnerability or susceptibility to addiction, so if your mom or dad or grandparent or aunt or uncle was addicted to alcohol, you’re more likely than someone without that family history to become addicted yourself. However, it doesn’t have to be to the same drug. Addiction is a disease that encompasses many different substances. Addiction is about substance-generated neuroanatomical and neurochemical changes that have profound similarities across a wide range of substances. The genetic component seems to result in an increased susceptibility to those substance-generated neuroanatomical and neurochemical changes that take place in addiction. Addiction also runs in families through other factors that are related to the environment in which someone grows up, such as social learning and observation. People who grow up in addicted families see how their parents or other relatives handle the stress of life by drinking and doing other drugs, and learn this as a primary coping strategy as well. Mommy gets depressed or anxious so she has a few drinks or smokes some pot to feel better. One’s community, neighborhood, and peer group are also powerful environmental influences. If substances are easily accessible and substance use is common where you grow up, you are much more likely to become addicted. If the group of friends you hang out with are all using regularly, you’re likely to use regularly as well. So the development of addiction is part genetic, part environmental, and part experiential/ neurochemical. 4 National Institute on Drug Abuse, “Twin studies help define the role of genes in vulnerability to drug abuse” (1999), http://archives.drugabuse.gov/NIDA_Notes/NNVol14N4/Twins.html (accessed June 13, 2013). 5 Kenneth S. Kendler and Carol A. Prescott, “Cannabis use, abuse, and dependence in a population-based sample of female twins,” American Journal of Psychiatry 155, vol. 8 (1998): 1016–22. 6 Kenneth S. Kendler and Carol A. Prescott, “Cocaine use, abuse, and dependence in a population-based sample of female twins,” British Journal of Psychiatry 173 (1998): 345–50. This blog post is an excerpt from The therapist’s Guide to Addiction Medicine – A Handbook for Addiction Counselors and Therapists – by Barry Solof, MD, FASAM; Published by Central Recovery Press (CRP).