Nawaf Alay- The Nature of Genetics

By Nawaf Alay

University of Florida

The Nature of Addiction 

           

Figure 1. A DNA strand.

 For the longest time both scientists and psychologists have debated the nature vs nurture concept. This concept involves nature; meaning the genetics of a person and nurture; the way the environment shapes a person. It takes into account both these aspects and uses them to understand why humans have certain behavior. Well, when it comes to the addictive behavior, it turns out that the argument still stands. Both genetics and the environment can build off each other in order to create a behavior in a person, however genetics may play a bigger role in addictive behavior than previously thought.

            Addiction is a very broad descriptive word that can be applied to many different behaviors, however, when a person is described as addicted to alcohol or drugs it becomes a negative behavior descriptor. A person facing addiction to substances such as alcohol and drugs may not be at fault due to the way their genetics are. Each individual possesses two alleles (genetic material that creates an individual’s biological makeup), one from their mother and another from their father and a myriad of these alleles come together to create the genetics of a person. There are so many alleles that come together that the amount of combinations that can be made is near to infinite. With this being said, the genetic makeup of a person is bound to affect a person’s personality as it seems everyone has a different behavior. A way a person is genetically mapped may create for more of an addictive behavior than another person who is not as genetically mapped to have an addictive behavior. The best way to prove this is by doing a twin study as identical twins are for the most part genetically the same. In this particular study done by Merikangas and Swendsen it was found that two identical twins living in the same environmental conditions may vary in alcoholic tendencies. After observing the twins from their teenage years up until their mid-twenties, it was found that one of them became reliant on alcohol while the other never engaged in alcoholic behavior. This can be a result from the genetic diversity of sexual production. One of the twins may have had a genetic makeup that was more favorable towards alcoholic tendencies. Although It can be argued that genetics played a part in this, it can also be argued that the environment played a role in one of the twin’s addiction. It is nearly impossible to keep an environment the same for two people as the people they meet may differ thus introducing them to different situations. For this reason, their environment (nurture) may have also shaped their alcoholism. In another family study it was also found that offspring from families that had a history of alcoholism were more likely to have a larger tolerance for alcohol than offspring from families with no alcoholic pasts. This presents an interesting point that the alcoholic genes are passed down.

            A method for better understanding the influence of genetics on addictive behavior is called molecular gene-finding methods. It useful because certain genomes (genetic material) code for different things in humans (just as discussed in the previous paragraph). By marking these genomes in different generations of humans, scientists are able to fins which gene-markers code for addictive behavior in people. Genetic-marking has helped find loci (places) on genomes that code for aggressive alcoholic behavior as well has genomes that code for addiction to substances such as drugs. Although this process finds very valuable information, it is still a pretty modern process and has many faults. For example, the genetic marker may not always be accurate or may not be able to find the exact gene. To better understand the role of genetics in addiction to alcohol scientist have attempted to breed rats in form called selected lines. This means that scientists will test rats based on their preferences to alcohol. They then separate the rats so that only rats that have similar preferences to alcohol may breed. Once this has been done, they check the preference levels of the offspring of the rats in each group. Through selected lines they have been able to find that the offspring of mice with a greater preference to alcohol tend to have a preference for alcohol, however not necessarily. In other words, the offspring of rats with a great preference for alcohol have a higher chance of having a preference for alcohol but are not destined to have that preference. Having a preference for alcohol is usually associated with addiction to the substance, and therefore leads to addiction. Therefore, we can assume that if they had let the rats become addicted to the alcohol, the offspring of the rats that were addicted to the alcohol would be more prone to be addicted to it.

            Through the multiple studies of genetics and its correlations with addiction we can conclude that although genetics play an influential role in addiction, it cannot be claimed that genetics are the sole reason a person becomes addicted to something. Although the twin study showed some very interesting points, no person can control the environment 100% so that two people endure the exact same situations. One twin may have had friends that were more prone to give into peer pressure and got into the bad crowd while the other one may not. Until we can prove what genes code for what behavior we must settle for the idea that both nature and nurture play a role in addictive behavior. 

References

Wensing, T. (n.d.). DNA [Digital image]. Retrieved from https://www.flickr.com/photos/thdoubleu/

Crabbe, J. C. (2012). Genetic Contributions to Addiction. Annual Review of Psychology,53, 435-462. Retrieved from https://www.annualreviews.org/doi/full/10.1146/annurev.psych.53.100901.135142.