Chimeras are mysterious, half-human, half-beast mythological entities whose presence is littered in the history and popular lore of several civilizations. The ancient Greek mythology portrayed chimeras as frightful creatures, which were in fact a combination of several animals. They sported the head of a lion, body of a goat and the posterior of a serpent .The Centaurs, perhaps the most widely mentioned chimera was the fusion of a horse and a man, was thought to be followers of Dionysius, the eccentric Greek God of fertility and wine.

This unique phenomenon is not solely confined to mythological beings but its repercussions can be felt and seen in practical life also. Human chimeras as a concept have already pooped up in several popular cultures. Whether it is  Michael Crichton’s medical thriller “Next” or a couple of episodes on popular TV shows like the CSI and House which were premised on chimerism, people always seem to adore such intense, bizarre scientific plotlines, no matter how fantastical the events may appear. However, with the advent of modern technology, especially genetic engineering, the line between reality and fantasy is increasingly getting blurred. Consequently, such bizarre humanoid entities may no longer simply be the stuff of science fiction and popular folklore or figments of our imagination. Human chimeras, in some form do exist in the real world, perfectly hidden amongst us.


Who are chimeric people?

One person outside but two persons inside, or a human being who carries the genetic framework or DNA of two separate individuals – this is the essence of a human chimera. The notion may seem outlandish but there have been several cases when a person has been found to be a perfect blend of two distinct people. Since 1950 when the first reported case of chimerism made headlines, nearly fifty cases of human chimeras have been documented since then. The scientific community is of the opinion that such rampant blending is more common at the cellular level which happens quite frequently, without or knowledge. Simply because one does not routinely test the cellular DNA of different parts of the body, so such chimeric anomalies largely remain undiscovered.


Reported Cases Of Human Chimeras

The very first case of a human chimera was reported in 1953 in the British Medical Journal , when a 52 year old women named Karen Keegan,  during the course of routine blood testing was found to be carrying two separate blood types. Astonishingly the results also revealed that she was not the biological mother of two of her three off springs. Although initially the possibility of child switching at birth was mooted, the unlikeliest of possibility of that occurring twice to the same parent, compelled the experts to look elsewhere for answers.

After extensive research for nearly two years, where various tissues of Jane were tested, the researchers were finally able to crack the riddle. They suggested that Jane was a rare case of human chimera, whose genetic framework carried traits of two separate individuals, the second individual being her twin brother whose cells got fused with Jane’s in their mother’s womb.

Recent studies have clearly substantiated that such blood group chimerism is more common than we may think. The second case of Chimerism was reported in 1998, when doctors while testing for an undescended testicle in a boy, instead found vestiges of female reproductive parts, parts of ovary and a fallopian tube.

The strange case of Lydia Fairchild in 2006 turned the concept of DNA testing as a reliable fail proof method of resolving paternity issues and criminal procedures, on its head. She was denied state assistance, when DNA results showed she is not related to her three children. Her inconclusive DNA results aroused suspicion of an elaborate attempt to scam the state and consequently Lydia’s appeal got rejected. Incidentally, Lydia was pregnant when she applied for state benefits. When she gave birth to her child and the same DNA test was again conducted, the results which again showed both the baby and the mother not being biologically related, flabbergasted everyone. In the light of the earlier reported cases, Lydia was tested for chimerism and the results came out to be positive. The aforementioned incidents clearly challenged the scientific community’s age old blind faith in the irrefutability of DNA testing. In light of the previously mentioned cases, it is quite clear that forensic science cannot rely solely on DNA testing for evidence and the current practices of resolving paternity and maternity issues, need to be reassessed.

Cause Of Chimerism

The most common cause of chimerism is fusion of two separateeggs in the mother's womb. That is why human chimeras represent an odd set of twins genetically fused into one body. If the fusion does not happen one will get normal fraternal twins, but in case it does, one will get a twin that is in normal sense not a twin at all. Obviously, one’s consciousness is not aware of this second individual nor there is any stark standout physical feature, although chimeras may have two eye colors or hair patches of different colors. The prominent changes are only seen at the cellular and genetic level.

A chimera will typically possess two separate sets of DNA , evidence of which will be found in different tissues and also sometimes may appear in the bloodstream.  Results ofDNA tests conducted on different tissues of a chimera will be similar to  DNA tests done on tissues of two separate individuals. The separate DNA may also be of both genders. Lydia Fairchild was eventually tested for this and the results came back positive. In a way, her twin was the mother of her children, at least, in a genetic sense. The case against her was subsequently dismissed.