NOV 10, 2015 07:05 AM PST

Could You Be Your Own Twin?

WRITTEN BY: Xuan Pham

In Greek mythology, a chimera is a fire-breathing beast made up of part lion, part goat, and part snake. Of course a trans-species hybrid is all fiction, but human chimeras are real and far more common than we suspect. In genetics and medicine, the term chimera refers to a person who biologically possesses more than one set of unique DNA materials.

Human chimerism involves a freaky vanishing act by a fraternal twin: Very early in embryonic development, two fertilized fraternal eggs occasionally join together with the death of one set of cells. The surviving cells can absorb the cells of its twin as it develops, resulting in a baby that contains a mixture of two sets of DNAs. This is known as tetragametic chimerism, or the vanishing twin syndrome.

Sound impossible? Until recently, scientists thought so too! But the many documented cases of chimerism show that not only is it possible, it probably happens more often than we suspect. The outward hints of chimerism are few, including different colored eyes (heterochromia iridium) or striping on the skin that's visible only with UV light (Blaschko's lines). Even so, the unique state of being a chimera can only be proven with extensive DNA testing, although these can sometimes be inconclusive. As such, many of us may be completely oblivious to our chimeric nature.

While chimerism is an utterly fascinating natural phenomenon, it presents unique challenges to blood-based DNA matching tests. Additionally, possessing two sets of DNA in your cells can complicate medical diagnoses and treatment outcomes. In short, being your own twin is wicked cool, but it can also carry a heavy burden of medical proof.
About the Author
  • I am a human geneticist, passionate about telling stories to make science more engaging and approachable. Find more of my writing at the Hopkins BioMedical Odyssey blog and at TheGeneTwist.com.
You May Also Like
NOV 19, 2019
Plants & Animals
NOV 19, 2019
How a Venus Flytrap Works
Most people think of plants as being at the bottom of the food chain, but the Venus Flytrap defies this oversimplified way of thinking by devouring meat. W...
NOV 19, 2019
Cardiology
NOV 19, 2019
Parkinson's Disease is Present in the Blood
Parkinson's disease is a progressive disorder of the nervous system. Often starting with a barely noticeable tremor in one hand, the disease affects a...
NOV 19, 2019
Plants & Animals
NOV 19, 2019
It's True, Elephants Are Highly Intelligent Animals
If you’re ever asked what the world’s smartest animal is, then the humble elephant should certainly come to mind. These incredible beasts have...
NOV 19, 2019
Earth & The Environment
NOV 19, 2019
The Amazon is Still Burning
Although other crises may be dominating international news headlines, the Amazon rainforest is still burning. The Wall Street Journal stated that more than...
NOV 19, 2019
Space & Astronomy
NOV 19, 2019
Starlink Aims to Provide Cutting-Edge Worldwide Internet Access
Almost everyone has heard by now that Elon Musk wants to launch well over 40,000 new satellites into space to deliver high-speed and low-latency internet t...
NOV 19, 2019
Space & Astronomy
NOV 19, 2019
Can We Terraform Mars?
Space agencies and commercial space companies are taking the idea of colonizing Mars very seriously. There’s just one problem: the red planet isn&rsq...
Loading Comments...