Nature vs. Nurture

Based on the fact that Marina and I are a monozygotic pair reared together (MZT), you would expect us to have identical personalities to the core. However, we happen to have many differences- while she is artistic, I can barely draw a stick-person. And whereas she has a knack of eating salty foods, everyone that knows me well can quickly say that I have the strongest sweet tooth out there. Nevertheless, we unquestionably share striking similarities as well. For one thing, we're both sporty (we've both participated in gymnastics, soccer, volleyball, swimming etc.), love shopping, are studious in school, and have a passion for traveling. Let it be said, I have often wondered what evoked our differences, since we are genetically identical and grew up in the same environment.

However, Marina, being my twin, understands me in ways other people don't. Although many friends that are close claim to be able to finish each others' sentences, my sister and I have an even deeper, freakish connection that our friends jokingly call our "twin telepathy."

L. Wright, who is mentioned in an journal about the renowned Minissota Study of Twins Reared Apart, says that "the science of behavioral genetics, largely through twin studies, has made a persuasive case that much of our identity is stamped on us from conception." This study, commonly known as MISTRA, addressed behavioral and personality differences and similarities between twins who were separated at birth and were met up years later. According to the article, monozygotic, or identical twins reared apart (MZA) had higher rates of personality correspondences than dizygotic, or fraternal twins reared apart (DZA). This points to the idea that genetics are truly a blueprint of our personalities.

Many cases show that the environment and social status of twins affect their personality, as seen in the case of  Mildred and Ruth, two fifteen year old MZAs. Ruth had grown up in a poor family that wasn't social, while Mildred wasn't brought up in a poor family and has "always been encouraged to make friends..." Psychologists claim that Ruth's unsocial, lonely upbringing may have led to her mindset of inferiority, while Mildred had a more "confident and more or less expansive" aura.

Therefore, it is my understanding that although the environment a person grows up in plays a key role in their personality, it doesn't makeup who they are and what they will be like, but rather influences the personality that has already been given to them in their genes.

The idea that our personalities may have been handed to us from the moment of our birth, only to be somewhat influenced by our upbringing is mind-boggling. This field of psychology is still fuzzy to scientists, and though they progress in their research and expand their knowledge on the subject, their findings continue to confound them. As L. Wright puts it, "The field of psychology has been shaken by separated-twin studies."

 Joseph, J. (2008). Separated twins and the genetics of personality differences: a critique. The American Journal of Psychology, 114(1), Retrieved from http://jayjoseph.net/yahoo_site_admin/assets/docs/AJP_MISTRA_PDF.157214425.pdf