The Fascinating Phenomenon of Conjoined Twins Quiz

Answer: 70%

70% of living conjoined twins are female, while 30% are male. No one knows for sure why.

Approximately 60% of conjoined twins conceived are either stillborn or miscarried. 35% of those that do survive birth die within 24 hours due to the level of conjoinment and complications. It is believed that conjoined twins occur in approximately 1 out of every 400 identical twin pregnancies.

Answer: The egg starts to split but fails to do so completely.

In this theory, a fertilised egg begins to split but is somehow interrupted in the process. The resulting embryos are conjoined. With most identical twins, the process begins in the first 12 days after conception. When the fertilised egg splits later than this, the embryo may be too large or too old to divide completely, resulting in conjoined twins. This is the most widely accepted theory.

Answer: The egg splits completely and then the two halves unite.

This theory holds that the fertilised egg actually splits normally. During development, like cells seek each other out and bond together to form different organs. While the two halves lie near each other, the signals may get mixed up and the similar cells attach to other cells of the same type which however belong to the other twin.

Answer: when the split happens

Both the degree that the egg splits and the time of the splitting are factors in determining how and where the egg splits. The twins can be joined anywhere on the body, but both will be joined at the same place.

Answer: by the site of the union

Clinical classification of conjoined twins is based on the major site of the joining plus the suffix "pagus" which means "that which is fixed".

The eight recognized configurations of conjoining are thoracopagus(chest), omphalopagus (umbilicus), pygopagus (rump), ischiopagus(hip), craniopagus (cranium), parapagus (side), cephalopagus (head),
and rachipagus (spine).

Answer: A conjoined twin that did not fully develop but is still attached to the other

A parasitic twin is vestigial to the healthy twin. A parasitic twin is not symmetrically conjoined, is less formed, and is dependent on the other larger twin for survival. Usually it is dealt with surgically as the parasitic twin may cause trouble for the healthy twin.

Answer: driver's licenses

These girls are truly remarkable. They are dicephalic parapagus twins, which means that they each have their own head, but share a body from the waist down. Brittany is on the left and Abigail is on the right. They have two spines which merge at the coccyx, and two separate spinal cords. They each have a set of lungs, each have their own heart, and their own stomach.

Brittany controls the left side of the body and Abigail, the right. These girls can walk, swim, play sports, ride bikes, and drive among other things. This is amazing considering that neither girl can feel her sister's limbs.

They took the driving test twice, once for each of them. Brittany controls the lights and turn signals and Abigail controls the pedals, heat, and anything else to the right of the driver. Both girls control the steering wheel. Each girl has her own driver's license.

Answer: They can see through each other's eyes.

Krista and Tatiana Hogan were born in 2006 in Canada and are craniopagus conjoined twins. Their brains are interconnected, making it impossible to separate them. They are unique girls, after extensive testing it has been determined that Krista is able to see through one of Tatiana's eyes and Tatiana can see through both of Krista's eyes. In addition, they seem to be able to taste what the other is eating.

Answer: Benjamin Carson

In 1987, Dr. Benjamin Carson successfully separated Patrick and Benjamin Binder who were joined at the back of the head. Dr. Carson lead the team which consisted of 70 members and who operated for a total of 22 hours. I made up the other names.

Answer: a malformed fetus found in the abdomen of its twin

People have lived for years with undiagnosed fetus in fetu. Two theories as to how this phenomeon occurs are: 1) It is a highly developed teratoma - a tumour inside an organ 2) It is a twin fetus that is enveloped within its twin.
The incidence of fetus in fetu is said to be approximately 1 in 500,000 births.