The Benefits & Drawbacks of Twin Studies in the Field of Psychology

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The Benefits & Drawbacks of Twin Studies in the Field of Psychology

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Twin studies are often cited for genetics purposes but these studies can be misleading in terms of similarities between people and predetermined genetic traits and dispositions. It is important to realize that genetics plays a significant part determining mentality and attitudes but genetics are not the sole determining factor for these traits. Genetics and hereditary predispositions explain some of the development of an individual’s characteristics; for example, temperament can be examined as a result of genetic dispositions. However, the environments in which a child is nurtured are numerous. These environments have multiple layers of forces that range from family and friends to school systems and governments. The multiple layers of environmental factors also contribute to temperament (Kowalski & Westen, 2009). These social and cultural factors play a significant role in psychological development, and twin studies show similarities but also wide ranging differences between similar genetics.

The study of identical twins provides a large benefit in that researchers can study the influence of genetics on behavior and mental health. Researchers have found that there is an 80–85% similarity between twins with regard to genetic traits such as intelligence and other developmental areas related to genetics. This research could be very beneficial in studying diseases such bipolar disorder to see if there is a strong genetic connection. However, the drawback to this research is that it appears that social influence has a strong impact. According to Thomas Bouchard “On average, identical twins raised separately are about fifty percent similar — and that defeats the widespread belief that identical twins are carbon copies” (Allen, 1998). This would seem to dictate that social influence has a very large impact on development. There may also be issues with studying twins having to do with research bias. There seems to be a tendency to emphasis similarities:

When journalists first began interviewing Bouchard’s twins-raised-apart, they focused on the spectacularly similar pairs, like the Springer-Lewis twins. But those twins turned out to be outliers in the Minnesota study. Most of the other twins weren’t nearly as alike (Allen, 1998).

Media tends to overstate the similarities between twins most likely due to the sensationalism of stories such as twins separated at birth who turn out to be similar in many aspects of their lives. These stories are abundant but they are anomalies. Researchers need to be careful not to look for similarities in this way or they may bias their results. Despite these drawbacks, twin research does offer a view of how genetics and environment mesh together in a person’s development.


Allen, A. (1998, January 11). The Mysteries of. Retrieved from The Washington Post Magazine:

Kowalski, R., & Westen, D. (2009). Psychology (5th ed.). Hoboken, NJ: Wiley.


Vincent Triola. Thu, Apr 01, 2021. The Benefits & Drawbacks of Twin Studies in the Field of Psychology Retrieved from

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