Sunday, March 1, 2015

Siamese Twins Question - And Information About The Rare Phenomenon

I was asked a basic question that I have no good answer for...I was asked:

"If Siamese twins wanted to go to college, would they both have to be accepted? Because the other one would have to sit in class with their twin. It's not like one twin could simply just cover his/her ears the whole time and not gather any of the information. Yet, there is no way they could go to different schools at the same time. Would they just have to pick which one had the better dream?"

First of all, I want to make sure everyone reading this knows that siamese twins are conjoined twins. 
Here is some information about them from Wikipedia:
Conjoined twins are identical twins[1] joined in utero. A rare phenomenon, the occurrence is estimated to range from 1 in 49,000 births to 1 in 189,000 births, with a somewhat higher incidence in Southwest Asia, Africa and Brazil.[2] Approximately half are stillborn, and a smaller fraction of pairs born alive have abnormalities incompatible with life. The condition is more frequently found among females, with a ratio of 3:1.[2]
Two contradicting theories exist to explain the origins of conjoined twins. The older theory is fission, in which the fertilized egg splits partially. The second and more generally accepted theory is fusion, in which a fertilized egg completely separates, but stem cells (which search for similar cells) find like-stem cells on the other twin and fuse the twins together. Conjoined twins share a single common chorionplacenta, and amniotic sac, although these characteristics are not exclusive to conjoined twins as there are some monozygotic but non-conjoined twins that also share these structures in utero.[3]
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Conjoined twins are typically classified by the point at which their bodies are joined. The most common types of conjoined twins are:
  • Thoraco-omphalopagus (28% of cases):[6] Two bodies fused from the upper chest to the lower chest. These twins usually share a heart, and may also share the liver or part of the digestive system.[7]
  • Thoracopagus (18.5%):[6] Two bodies fused from the upper thorax to lower belly. The heart is always involved in these cases.[7]
  • Omphalopagus (10%):[6] Two bodies fused at the lower abdomen. Unlike thoracopagus, the heart is never involved in these cases; however, the twins often share a liverdigestive systemdiaphragm and other organs.[7]
  • Parasitic twins (10%):[6] Twins that are asymmetrically conjoined, resulting in one twin that is small, less formed, and dependent on the larger twin for survival.
  • Craniopagus (6%):[6] Fused skulls, but separate bodies. These twins can be conjoined at the back of the head, the front of the head, or the side of the head, but not on the face or the base of the skull.[7]
Other less-common types of conjoined twins include:
  • Cephalopagus: Two faces on opposite sides of a single, conjoined head; the upper portion of the body is fused while the bottom portions are separate. These twins generally cannot survive due to severe malformations of the brain. Also known as janiceps (after the two-faced god Janus) or syncephalus.[7]
  • Syncephalus: One head with a single face but four ears, and two bodies.[7]
  • Cephalothoracopagus: Bodies fused in the head and thorax. In this type of twins, there are two faces facing in opposite directions, or sometimes a single face and an enlarged skull.[7][8]
  • Xiphopagus: Two bodies fused in the xiphoid cartilage, which is approximately from the navel to the lower breastbone. These twins almost never share any vital organs, with the exception of the liver.[7] A famous example is Chang and Eng Bunker.
  • Ischiopagus: Fused lower half of the two bodies, with spines conjoined end-to-end at a 180° angle. These twins have four arms; two, three or four legs; and typically one external set of genitalia and anus.[7]
  • Omphalo-Ischiopagus: Fused in a similar fashion as ischiopagus twins, but facing each other with a joined abdomen akin to omphalopagus. These twins have four arms, and two, three, or four legs.[7]
  • Parapagus: Fused side-by-side with a shared pelvis. Twins that are dithoracic parapagus are fused at the abdomen and pelvis, but not the thorax. Twins that are diprosopic parapagus have one trunk and two faces. Twins that are dicephalic parapagus are dicephalic, and have two (dibrachius), three (tribrachius), or four (tetrabrachius) arms.[7]
  • Craniopagus parasiticus: Like craniopagus, but with a second bodiless head attached to the dominant head.
  • Pygopagus (Iliopagus): Two bodies joined at the pelvis.[7]
  • Rachipagus: Twins joined along the dorsal aspect (back) of their bodies, with fusion of the vertebral arches and the soft tissue from the head to the buttocks[9]

My response is that I believe the two would be accepted together, and that is simply because if they are joined in a way that cannot be separated, then they will need to share their future together, anyways. However, I have never experienced this lifestyle, and I am sure this decision would be a very difficult one.

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