What would it be like to have a twin? This is a question people often ponder. People often say that they see someone that resembles someone they already know. It is almost like dejavu. "Twin" comes from the German word "twine" meaning "two together" (Nagy 1). Most people automatically think of two people who look just alike when they hear the word "twin". However, there is a lot more to twins than just looking alike. Twins are the most common type of multiple births. Many think there are only two types of twins, identical and fraternal; they often leave out conjoined twins. Twins are very unique and fascinating individuals because of their similarities biologically, physically, and psychologically.
An author from the twin's network stated that, "A British scientist was the first to say that identical twins are identical biologically and may have come from a single egg" (Nagy 1). He was correct when he made this hypothesis. Identical twins form when a single fertilized egg splits usually one to fourteen days after conception (Wade 53). Identical twins are the same sex, they have the same chromosomes, and are the same blood type. Identical twins also mean monozygotic twins. According to the twin's network, studies show that identical twins live longer than fraternal twins; they believe this is due to their close communication (Nagy 1). Fraternal twins are the most common type of twins. They are the result of the union of two eggs and two sperm. Fraternal twins can be the same or different sexes (Wade 53). Segal says that, "They are two individuals, no more genetically alike than brothers and sisters that develop from separate fertilizations" (Segal 1). Amazingly, fraternal twins can be conceived at separate times and have different fathers. It seems to be a hereditable trait to conceive fraternal twins. Yet, tendency to conceive conjoined twins may be caused by genetic and environmental conditions (Hunter 1). Conjoined twins are the rarest type of twins. Conjoined twins were once known as "Siamese twins." Conjoined twins originate from a single fertilized egg so they are always identical and same sex twins. The developing embryo starts to split into identical twins within the first two weeks after conception but stops before completion. A partially separated egg is left of the embryo, and it continues to mature into a conjoined fetus (Hunter 1). Conjoined twins can be joined at the hip, chest, abdomen, buttocks, head, or internal organs (Scheinfeld 37). The overall survival rate for these twins is somewhere between five and twenty-five percent (Sanders 2). This means that the majority of conjoined twins die within twenty-four hours of birth. For the few who survive the traumatic beginning, surgical separation is often possible for conjoined twins. The average survival rate after surgery is around forty-six percent (Sanders 2). This percent depends greatly on the location of the attachment and the organs that are shared. There is some controversy over the separation of conjoined twins. In some cases separation has turned into a moral issue. A prime example of how dependent one twin is on the other is in the case of the British conjoined twins, Jodie and Mary. Jodie was stronger and more capable than her sister. Mary was weak and was only alive because she was attached to Jodie. However, Mary's weakness would eventually make Jodie weak as well. The parents were burdened with a moral dilemma, which would result with the loss of at least one child (Sanders 4). If Mary and Jodie were separated, one would likely die. Some separations are more difficult to complete than others. Parents of conjoined twins have to think about all of the factors before they proceed with a separation. There are also factors to think about after separation. If both twins survive the separation, they may still need an enormous amount of medical treatment throughout their life. In...
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