An addiction to alcohol, also referred to as alcoholism or alcohol dependence, is at least partly determined by genes. This does not mean that if your parents were alcoholics, you are doomed to become an alcoholic yourself. Instead, it means the risk is increased and you should be careful with your use of alcohol.
Scientists have shown that alcoholism has a genetic basis by using adoption studies and twin studies and demonstrating that if a biological parent is an alcoholic, an "adopted-out" child has an elevated risk for alcoholism. In fact, in the few cases in which the adoptive parents were alcoholics, as long as the biological parents were not alcoholics, the adopted person was not at risk for alcohol dependence.
Adoption Studies and Alcoholism
Virtually every adoption study of the risk for alcoholism shows that there is a clear genetic risk for this disorder among adoptees. Most adoption studies have been performed in Sweden or Denmark, where access to information about adoptees and their biological parents is readily available. For example, research from the Stockholm Adoption Study has shown that if an adopted man had a father with alcoholism, then the adoptee had a six times greater risk for becoming an alcoholic himself. Some adoption research has been performed in the U.S., and researchers on the Colorado Adoption Project have found that a genetic risk for alcoholism is a significantly greater risk factor for developing alcohol dependence than any environmental risks.
Twin Studies and the Risk for Alcoholism
Studies that date back to 1960 have demonstrated that if one identical twin is an alcoholic, the other twin has about a 76 percent risk of also becoming an alcoholic. Fraternal twins have a risk of about 26 percent if one twin is an alcoholic.
Some researchers have looked at identical twins who were separated at birth and studied their risk for alcoholism. For example, in one study published in 2004, the researchers found that a twin raised by a biological mother had an elevated risk of alcohol abuse compared to the twin who was adopted. The researchers stated their belief that the environment of the adopted twin was superior to the environment of the non-adopted twin, and this factor may have mitigated against the development of an alcohol problem. Thus in this case, environment apparently trumped heredity.
Low Intensity Response
Some researchers such as Marc Schuckit have found that the individual's personal response to alcohol affects whether they become alcoholics; for example, in one study, the researchers found that the sons of alcoholic fathers said they had fewer problems with sleepiness and dizziness when they drank. This "low intensity response," likely an inherited factor, apparently led the sons to drink greater quantities of alcohol and be at a higher risk for alcoholism than the sons with an average response. Simply put, if alcohol makes you feel great and with few or no ill effects, then you may have a greater risk for using and abusing alcohol. In contrast, if alcohol makes you feel very ill, you have a lower risk for alcoholism.
Some people, particularly Asians, have an automatic "flushing response" to alcohol and consuming alcohol causes them to become red-faced. Some become very ill from drinking alcohol and even a small amount causes nausea and vomiting. These individuals have an inherited inability to metabolize alcohol--and they are extremely unlikely to become alcoholics.
References
- "Journal of Substance Abuse Treatment", An Overview of Genetic Influences in Alcoholism."Marc A. Schuckit, M.D.", "2009".
- "Archives of General Psychiatry", "Genetic and Environmental Contributions to the Development of Alcohol Dependence in Male Twins", I-Chao Liu, M.D", "2004".
- "Archives of General Psychiatry", "Replication of the Stockholm Adoption Study of Alcoholism: Confirmatory Cross-Fostering Analysis", Soren Sigardsson, Michael Bohman and C. Robert Cloninger", 1996.
