Out of approximately every 400,000 births, four are conjoined. Of the four, three will die within twenty-four hours. Of the remaining set of twins, 70% of them will either die (one or both) or they will live out their lives handicapped. The overall survival rate for conjoined twins is between 5% and 25%. Considerably more males conjoin in the womb than females; however females are three times as likely as males to be born alive. Approximately 70-75% of conjoined twins are female. Conjoined twins who survive are truly miracle babies. They are a medical phenomenon, and even more so in society, for the survival rate of conjoined twins is so low that meeting conjoined twins that survived is a rare occasion.
Conjoined twins, defined by Stedman’s Medical Dictionary, is:
“Identical twins born with their bodies at some point and having varying degrees of residual duplication, a result of the incomplete division of the ovum from which twins developed.”
Simply put, conjoined twins are twins whose bodies are joined together at birth.
There are many different names for conjoined twins, however the two most common are conjoined and Siamese. The word Siamese most likely originated from the twins Chang and Eng who were from modern day Thailand. Both words however refer to twins who are a form of monozygotic twins. Monozygotic twins are formed when a single fertilized egg splits into two embryos. Or perhaps in an easier to understand way, conjoined twins are formed when the zygote (a cell that is the result of fertilization) of identical twins fails to completely separate. This failure of the zygote to completely separate is not affected by heredity, infertility treatments, maternal age, or any other factors. The cause of the birth of conjoined twins is really unknown, and at this point completely random.
There are several conjoined twins now present in the world, most of which have been featured in some kind of news article or TV show. Some of the most famous conjoined twins are Chang and Eng Bunker, and Mary and Eliza Chulkhurst. Chang and Eng were Chinese Americans born modern day Thailand in 1811 and are most likely responsible for the term Siamese Twins being coined. Mary and Eliza are the earliest known set of conjoined twins. They were born in 1100 in Biddenden, Kent, England.
There are many different types of conjoined twins, depending upon where the twins are joined together.
During ovulation, when a woman releases an ovum, three different processes can occur. First, the ovum can remain in one piece all the way to the uterus where, if not fertilized, it will be shed out of the body along with the unused endometrium. Second, the ovum, if fertilized, can develop into a single embryo, which is the most common type of pregnancy in humans with about 99% of all births being singletons (1). Finally, the ovum can split into two separate halves resulting in genetically identical twins. The three types of twins previously mentioned are identical, which are created when the fertilized ovum separates into two complete, identical parts, conjoined, which occur as a result of a fertilized ovum not completing the equal separation resulting in two fetuses fused together in some way, and half-twins or polar body twins, which are made when an unfertilized ovum splits into two complete, identical parts and is then fertilized by two different sperm. The frequency of identical twins is 3.5 per 100 births (1) and the frequency of conjoined twins is 1 birth per 50,000 with only 100 known cases surviving their first year (5).
...reversals that question the validity of that assumption. She believes that it is more important to recognize the fact that twins and other multiplies try to find ways to distinguish themselves from each other (p. 124).
As I walk through the crowded mall with my sister, little children stare, most adults do a discreet double take, and some bold adults question us outright. “Wow, are you twins?” “Do you know you look the same?” “What’s it like to be a twin?” “Do you have, like, psychic powers, or something with each other?” These are the most common questions twins hear. Almost all twins don’t really mind them and sometimes the attention is cool. Mostly, we just smile tolerantly at each other and answer them as best we can. After all, we don’t really know how to describe being a twin. We have never known anything else. Nonetheless, here we are. So, as a person who might not know exactly what she is talking about, I will try to briefly explanation to the general public the experience of being a genetic quirk.
Many environmental, genetic, and emotional factors are related to the composition of twins. Any types of twin share a relationship that most people will never experience. Twins, whether fraternal, identical, or conjoined, are an amazing phenomena of human life.
I have always been fascinated by conjoined twins and have always had questions about them like; what do the Siamese have to do with conjoined twins? Why does this form of twin happen? What, if any genes cause this? What types of Conjoined twins are there? How does the environment affect, if at all, the biological families' gene pool? In my research in efforts to prepare this paper, I found the answers to this question and many more. This term paper will cover the types of conjoined twins, the biological occurrence that causes conjoined twins, a look into some of the genetic and environmental causes of conjoined twins, the types of conjoined twins and the genetic and social impact of conjoined twins.
On October 9, 1968, a set of twins were born, but separated at birth and ultimately, put up for adoption. The decision to separate the twins came from the adoption agency who wanted to conduct a nature versus nurture experiment; however, the experiment was conducted in secret. However, for unknown reasons, the experiment never developed to fruition. Unaware the child they adopted was a twin; both sets of parents raised a singular child. Thirty-five years later, one twin began a search for her biological mother through the adoption agency, only to find out that she was born a twin. Upon learning her identity, she reached out to her twin and they began the journey of getting to know one another by comparing characteristics that appeared similar such as temperament and mannerism. They even discovered that they both held positions as a film critic and enjoyed almost identical movies.
Conjoined twins, from the moment they enter the world, face a myriad of social, physical, psychological, and health problems. If one or both of the conjoined twins’ major body parts cannot properly function, they usually die within a few days. The births of conjoined twins are when the skin and internal organs are fused together, which only happens in every 40,000 births. The ratio for the sex of conjoined twins is 3:1, the 3 being the girls. Conjoined twins are increasingly accepted into our everyday lives as we grow to understand their unusual physical and emotional bond and learn more about the science behind their development.
There are more twin babies conceived now than there used to be since the eighties. “One in every 30 babies born in 2009 was a twin (a 76 percent hike since 1980),” (Goldman, L. Web source). Twins are born in different varieties. They can be fraternal or they can be identical. Identical twins can be either both brothers or they can be both sisters. If they are sister and brother they are said to be fraternal.
Dr. Eileen Pearlman says that “The separation and individuation process begins early in life, and for some twins it takes longer than others as not only do twins need to learn to separate and individuate from their mothers but they also have to learn to separate and individuate from each other.” The constant comparison from individuals looking into their life can make this harder for twins. People need to understand that with being a twin there are advantages but also disadvantages. People and even family members of twins can fail to realize this. The figment of people's imagination is that twins get along, have similar tastes, and are the exactly alike, almost the same
a single egg or the fertilization of two eggs. In the case of dizygotic twins,
At the University of Minnesota undergrad students conducted a long term project where more than 350 pairs of twins went throug...
In the twin study method, researchers studies identical twins (monozygotic twins) and fraternal twins (dizygotic twins) to determine how much they resemble each other on a variety of characteristics. Identical twins have exactly the same genes because a single sperm cell of the father fertilizers a single egg of the mother, forming a cell that then splits and forms two human beings-"carbon copies." But fraternal twins are no more alike genetically than any two siblings born in the same parents. In the case of fraternal twins, two separate sperm cells fertilize two separate eggs that happen to be released at the same time during ovulation.
Conjoined twins, more commonly known as Siamese twins because of Chang and Eng Bunker, are considered extremely rare among populations. According to the University of Maryland Medical Center, births of conjoined twins occur only once out of every 200, 000 births. Twins become conjoined when an embryo starts to divide but fails to complete the process. While the twins become a single entity, they are considered separate individuals. However, most conjoined twins do not survive after birth and when they do they tend to have problems with malformed organs that are shared. The research by the University of Maryland Medical Center concludes that the overall survival rate of these conjoined twins is somewhere between 5 and 25 percent. With that being said, conjoined twins are often viewed as curiosities and a rare occurrence in our society in general.
Those who have arrived at the ovum try to drill through its shell. Those sperm cells that were able to drill through the shell are now in a space that is filled with liquid. If a sperm manages to penetrate into the cytoplasm of the cell nucleus, the fertilization takes place: Both the egg cell and the sperm cell have all stored the genetic information necessary for the development of a human being. Both fuse together during fertilization. Essential characteristics of the developing human being (gender, hair color, blood type, etc.) are therefore already defined from this point in time. Fusing of two sperm with just one egg is extremely unlikely. Immediately after fertilization by the first sperm cell, the outer layer of the “egg” becomes impassable for more sperm. Should it nevertheless occur, then the double-fertilized egg in these cases is not viable and will not usually grow. The child (so to say) is not able to correctly develop and severe disabilities can form, in most of these cases the body will discard the fertilized egg at some point. If the child is carried to full term they will most likely be triploid, and have an extra set of chromosomes in their cells. Triploidy is considered a lethal
I. The Dangers: As mentioned before, two-thirds of the 42,000 highway deaths last year were related to aggressive driving.