NOV 10, 2015 07:05 AM PST

Could You Be Your Own Twin?

WRITTEN BY: Xuan Pham
2 8 1483

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
JUL 05, 2018
Videos
JUL 05, 2018
Can Food Be Prescribed?
Hippocrates, the father of medicine was famous for saying, "Let food be thy medicine and medicine be thy food” and what he meant was that eating
JUL 09, 2018
Videos
JUL 09, 2018
Does Microwaving Food Affect It's Nutritional Value?
  Microwaving is a convenient way to heat food with ease and in short periods of time. But, do microwaves change the nutritional value of food? Microw
JUL 21, 2018
Videos
JUL 21, 2018
The UK's First '3 Person Baby'
Mitochondria carry their own genetic material, which is only inherited from mom.
AUG 01, 2018
Videos
AUG 01, 2018
Goodbye to the Endangered Species Act?
The Endangered Species Act, which protects more than 2,000 plant, animal and insect species at risk of
AUG 11, 2018
Videos
AUG 11, 2018
Hit The Sweet Spot - MIT's Image Awards
MIT researchers are trying to engineer a smarter insulin.
AUG 13, 2018
Videos
AUG 13, 2018
What does sunscreen look like with a UV camera?
  Have you ever wondered if there’s really a difference between SPF 30 and SPF 50? You’re not the only one. YouTuber Physics Girl set out
Loading Comments...