This essay discusses twin studies with particular emphasis on the role of genetics on intelligence and personality characteristics. There has been an ongoing debate whether intelligence and personality is based on genetic predisposition or not; and basing from existing literature, twin studies show significant evidence that genes do play a significant part. Separated Twins Twin studies have been beneficial and informative regarding the mentioned debate. Identical twins become a good medium to learn from as they are 100% genetically the same. In a situation where the twins are separated and reared apart, what happens?
In a work written by Lawrence Wright, he relates the story of female identical twins that grew apart and was reunited. He said that since they are genetically the same, “one could evaluate the environmental effects on the twins’ personalities, their behavior, their health, their intelligence” (1997). In this particular study, the twins, Amy and Beth, were brought to two separate homes after birth. Amy was placed in a family where she was seen as a problem and was treated like an outsider. Amy’s mother was physically unfit and suffered from low self esteem.
In contrast, Beth was treated well in the family she was adopted in and her mother did everything she can to make Beth a real part of the family. The results showed that during childhood, both child manifested same habits as “thumb-sucking, nail-biting, blanket-clenching, and bed-wetting. (1997)” Moreover, they were both afraid of being left alone. Both had school problems and problems among friends and schoolmates. Though Amy had a good mother, her psychological tests show she had “a longing for maternal affection,” which as maintained by Wright “was eerily the same as her identical sister’s” (1997).
Apparently, basing from the results of the study, despite growing up in different conditions, Amy and Beth were alike pathologically (Wright 1997). In addition to this, Wright mentions that “Matters that instinctively seem to be a reflection of one’s personal experience, such as political orientation or the degree of religious commitment, have been shown by various twin studies to be partly under genetic control” (1997). This demonstrates how significant a part genetics play alongside environment.
On the basis of this study, Wright believes that despite external factors, genetics still rule and determine a person’s traits. Conclusion Despite the significance of twin studies, especially like in the case of Amy and Beth, it appears that much of what a person becomes may be considerably attributed to genetic factors. However, as Wright himself says, this matter has been debated on for centuries. On regards intelligence, it still cannot be established as there are variations among IQ results of both fraternal and identical twins.
According to Medical News Today, there are indeed hereditary factors that affect the size of the brain. However, “the mechanisms by which interaction between genes and environment occur throughout life as well as dynamics of brain structure and its association with brain functioning still remain unknown” (2007). This suggests that further studies regarding the matter is necessary to arrive at a conclusion. Twin studies will continue to be useful in further discoveries on the study of genetics and its relationship with human intelligence and personality development.