Final

Kimberly O’Day
Professor Yerks
Comp 106
23 April 2010

The nature verses nurture debate has been a heated argument for decades, only recently has there been any grounded evidence found to support either side. How much does your genetic code play in to the development of self? The recent use of twin studies has opened the eyes of many toward the extent to which genetics play in every individual’s life. Twins studies are a technique used by individuals from all sects of the academic community. These studies have been used to determine the likelihood of an individual inheriting an illness, the extent to which you DNA affects your IQ, how much of your personality is in your predetermined in your genes, etc.

In order to interpret the data from a twin study or understand their importance you must first know a minimal amount of background on twins. Not all twins are the same; this is an important aspect in looking at the studies. Fraternal twins are created when a mother releases two eggs which are in turn fertilized by two separate sperm. They are genetically no different than any other siblings except that they were born at the same time, thus they share 50% of their genetic make up. Identical twins are created when a single egg is fertilized by a single sperm and then divides. These twins are said to be identical because they have the exact same DNA, thought they often differ in personality and appearance. Through this knowledge we are able to determine to what extent genetics plays on a persons development and how much can be influenced by our environment, by comparing the results from a set of fraternal twins to that of a set from identical twins.

The largest frequency of twin studies generates in the field of psychology. There has been research conducted to determine whether an individual may have a predisposition to any variety of mental health issues. In a study conducted by Gottesman shows that the likelihood of an individual being diagnosed with schizophrenia in his or her lifetime is seventeen percent if they have a fraternal twin that has previously been diagnosed, if that individuals twin that was diagnosed was his or her identical twin the likelihood of this individual being diagnoses rises significantly to forty eight percent (Twin Study Overview). While there is a large difference in percentage between identical and fraternal twins it is important to look at the likelihood of any single individual in the population being diagnosed with this disease that likelihood rests at only one percent. This without a doubt leaves the impression that genetics must play some role in the way in which we acquire mental disorders.

This paper would not be complete without a look at the most controversial media covered topic in recent time, the homosexual community. In order to push legislation through our government activist groups have been attempting to compile data showing that an individual is born gay, it is not a conscious choice that these people make. This statement seems to make a lot of sense, in our society today those who come out, although being true to themselves, are knowingly making their lives harder. It seems illogical that they would choose to take a rougher path than those of us that are heterosexual. Those looking to this outlet to confirm the reason for their homosexuality have fallen short. The instance of both identical twins being homosexual is only thirty eight percent; if homosexuality were like eye color, something your genes determined, the instance of both identical twins being homosexual would be one hundred percent (Whitehead). This data will likely be shown through the media by Republican politicians in order to continue their support of the traditional household.

Though I have only touched on a small sect of topics that twin studies are used in the results all yield to the same conclusion. Neither nature nor nurture alone can determine the outcome of an individual’s life. In many areas of inquire genetics may play a role in which traits become visible, but the extent to which these genes affect specific traits varies. One may have a predisposition to a whole slew of mental health disorders, yet if they are raised in an environment that has shielded them from the things that may trigger the onset of these diseases they could live their whole lives without ever being presented with a single symptom. The environment in which a person is raised has a large bearing on the outcome of their lives. “Genes create a tendency, not a tyranny” as stated by N.E. Whitehead PhD, author of The Importance of Twin Studies.

In twin studies there are some factors that leave experts wanting more. When a twin study is conducted it is expected that the twins are growing up in the same environment being exposed to identical external factors. This however is impossible to control. While twins are born at essentially the same time it is often found that the minutes in between their births play a role in how their personalities form (Rutter). As a general rule of thumb those who are first out of the womb will take on a typical oldest child role in the family while the second born will take on the role of the baby of the family, assuming the twins are the only children to their parents. This is assumed to be due to the way in which the parents treat their twins. Although identical twins share the same genetic make up they see the world through their own set of eyes, thus leading to different perspectives that could influence the way their separate personality forms. It is common for twins to be separated into different classrooms once they reach school age so that they can develop their own self, this creates a problem for those generating theses studies because the twins who are essentially the same are being exposed to different experiences. I would be hesitant to say that conjoined twins experience the exact same world; if you have two separate eyes to take in the world and two separate brains to process the intake that is to say those they perceive the world the same as one another. Even rarer is the set of identical twins that were reared apart, such as in the case of separate adoptions. This is an ideal situation for a researcher. The twin’s share the same genes yet have separate experiences based on their environment. In this rare occasion it is possible to determine with a higher rate of accuracy what role genes play in the nurture verses nature debate.

Twin studies have a long road ahead of them. It can not be said with any definitive rate of accuracy as to what role our genes play in our development. We grow as a society with every advancement made whether in your particular field of study or one you know little about. Researchers studying twins for any reason have a bright future to look forward to due to the recent medical advances in obstetrics; the use of in vitro fertilization has a high likelihood of creating a pregnancy resulting in a multiple birth thus dramatically our pool of possible subjects. For the time being, twin studies give a slight glimmer of hope to an end of this long standing debate.


Works Cited

Rutter, Michael, and Jane Redshaw. "Growing Up as a Twin: Twin-Singleton Differences in Psychological Development." Journal of Child Psychology and Psychiatry and Allied Disciplines 32 (1991):885-895. 15 Apr 2010.

"Twin Study Overview - Dealing With Schizophrenia." Nature vs. Nurture. Web. 08 Apr 2010.

Whitehead, N.E. "The Importance of Twin Studies." National Association of Research and Therapy of Homosexuality. Web. 08 Apr 2010.

The survey I conducted on twins yielded some very interesting results. My survey contained responses from sixteen individuals, the survey was open to anyone who had close contact with a set of twins. The surprising thing was that most individuals who took the survey knew relatively little about the twins that were present in their lives. If I were to analyze the results for this survey I would have to disregard all responses from individuals who were not the parents of the twins regarded in this survey due to the lack of substantial knowledge on the twins. A third of the participants were indeed a parent of twins. What I found most surprising when looking at the data I had collected was half of the parents who claimed to have a set of identical twins did not know what type of identical twins they were. After contemplating this discrepancy there are a few conclusions I have arrived at: The parent in question was a father, in which the type if identical twins he fathered would not be necessary information since he was not the one carrying the fetuses; the twins were born before medical equipment was discovered that could tell the way in which a mother was carrying identicals (although this was not the case in the survey all identicals were under the age of eight); lastly, it was never medically defined as to what type of twins the set in question really were which could cause the data to be misleading if they were in fact not identical but fraternal twins that happened to look very much alike. The parents were the only group that could tell me whether the twins were co-bedded, which I asked to determine the extent to which the twins were kept together after birth, possibly showing another reason for a close bond shared after birth. I wanted to look to whether identical twins were closer than fraternal twins. Throughout the questions and stories offered in this survey it seemed to show that identical twins do indeed have a stronger type of bond than fraternal twins. More would need to be done since this was such a small sample and it was voluntary participation. If I could do it again I would include more open ended questions as well as make stricter stipulations as to who is eligible to take the survey. Overall I found the results very interesting.