We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What are Conjoined Twins?

Tricia Christensen
Updated May 17, 2024
Our promise to you
WiseGeek is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At WiseGeek, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Conjoined twins are twins, almost always identical, who are connected through skin, organs or other parts of the body. They are frequently inaccurately referred to as "Siamese" twins, probably in part due to Chang and Eng Bunker, twins born in Siam who traveled with P.T. Barnum’s Circus during the 19th century. The term is inaccurate since conjoining occurs throughout the world at a rate of about 1 in 400,000 live births.

In most cases, on the 13th day after a pregnancy begins, twins separate into their own egg sacks, and each twin creates a placenta. When conjoined twins occur, this separation has failed to take place, and researchers do not know the cause. They suggest contributory factors may be environmental or genetic. Classification of such twins rests on the way in which they are joined, and this joining exhibits a great deal of variation.

Survival and ability to separate the twins depends upon the type of conjoining. While some can do very well after separation, in other cases, dividing them may be impossible, or may mean the loss of life of one of the twins. If the children share vital organs, separation is far more difficult, as organs tend not to be split. This is the case with twins joined at the spine as well, as surgery can frequently cause paralysis or death.

In some cases, conjoined twins have one healthy twin, and one that is very unhealthy, called parasitic. In these cases, separation is necessary to protect the healthy child. It is frequently tragic and difficult for parents to make such decisions, since agreeing to separation surgery is essentially agreeing to allow one child to die. On the other hand, the choice not to separate parasitic twins usually means that both twins will die.

When conjoined twins cannot be separated, they frequently are able to manage through living a very different lifestyle. Difficulties occur when the twins share the same reproductive system, or excretory pathways. Others suffer from postural difficulties if they are joined at the head. Life expectancy for twins who cannot be separated frequently depends on how many organs are shared. If the heart, lungs, liver, or kidneys are shared, providing the work for two bodies may be very difficult. In some cases, the conjoining is almost always fatal during the first few days of life.

Twins who share a heart have a low rate of survival. Those who share a heart and brain tend to be considered non-viable. In other cases, called inclusion twinning, one twin absorbs the body of a dying sibling while still in utero. Sometimes, the surviving twin must undergo surgery to removed skeletal portions of the other’s body.

Literature and film have always been fascinated by conjoined twins. Mark Twain wrote a novel and several short stories regarding them, and they were often exhibited as “freaks” in circus shows. The film Stuck on You, starring Matt Damon and Greg Kinnear, was a humorous but insightful portrait of this condition.

Separation attempts seem most successful in Saudi Arabia, where nine separations have been performed in the last 15 years with a 100% survival rate. Usually, medical professionals will not undertake separation without the possibility of at least one of the children surviving the surgery. The courts have sometimes stepped in, as in England, where a judge ordered the separation of two children despite the parents’ strong objection. The two twins were parasitic, and the weaker twin did die. It is hoped that, with greater understanding and perhaps with improved fetal surgery techniques, rate of survival in separation may increase, offering conjoined twins the same chance as other infants to live a healthy and productive life.

WiseGeek is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Tricia Christensen
By Tricia Christensen
With a Literature degree from Sonoma State University and years of experience as a WiseGeek contributor, Tricia Christensen is based in Northern California and brings a wealth of knowledge and passion to her writing. Her wide-ranging interests include reading, writing, medicine, art, film, history, politics, ethics, and religion, all of which she incorporates into her informative articles. Tricia is currently working on her first novel.
Discussion Comments
By anon9461 — On Mar 06, 2008

This article will be perfect for my research paper! Thanks!

Tricia Christensen
Tricia Christensen
With a Literature degree from Sonoma State University and years of experience as a WiseGeek contributor, Tricia...
Learn more
WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.

WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.