- Imagine being told that a sibling you don’t have lives in your body.
It’s always a difficult situation if you find out your parents aren’t whom you think they are. Unless, of course, the whole thing is so bizarre that you’re more confused than upset.
For example, you could find out that your mother is also your uncle. And possibly your father.
A routine paternity test on a young girl revealed this mind-boggling scenario in one anonymous family, raising complex issues around paternity law and child custody.
Juan Yunis, the scientific director of Servicios Médicos Yunis Turbay y Cia in Colombia, detailed the outlandish test results in an interview with Grid. We’re not even sure where to begin, so let’s just go through everything in order.
First, some parts of the results suggested that the mother was not the girl’s mother. Considering that she and the father knew the woman had given birth to the girl, the result was a tad strange.
Things got more awkward when other results implied that the girl’s father hadn’t actually fathered her. However, the third outlandish result probably silenced any possible questions the father may have had.
A blood sample taken from the mother indicated that she was not a woman. Her sample contained the XY chromosomes of biological males, instead of the XX chromosomes found in women.
Naturally, Yunis had trouble believing the results.
“Somebody made a mistake, there’s contamination in the lab, stop everything,” he recalled saying.
The doctors repeated the tests, but this time, left the mother out of it. All of a sudden, it was clear as day that the girl’s father was her father.
So, what on Earth was going on?
The Brother She Swallowed
Yunis and the rest of the medical initially scratched their heads in as much confusion as the girl’s parents. But then Yunis remembered something from two decades ago.
In 2002, he had been part of a team carrying genetic tests on one Karen Keegan in anticipation of a kidney transplant. They’d discovered something unusual — her genetic makeup consisted of two pairs of egg and sperm cells.
She was a human chimera. And it was the same situation with the woman from the paternity test.
A chimera — named after the mythological creature that’s a mash-up of multiple animals — is a single organism made up of cells from multiple separate individuals. In mammals, chimeras are born when two (or sometimes more embryos) merge during pregnancy.
In other words, the mother who took the paternity test cannibalized her brother in the womb.
“The child’s mother is a natural chimera. One twin (a male) fused with the other (female) twin and disappeared early in pregnancy,” explained Robert Wenk, a Baltimore-based genetic pathologist.
Having realized what he was dealing with, the results of the paternity test suddenly made sense to Yunis. The strange male that appeared in the test was none other than the woman’s twin brother who continued his existence in her genetic makeup.
To confirm the theory, Yunis’ team took samples from different parts of the woman. And sure enough, her blood and saliva showed XY chromosomes, while the cells on her cheeks and hair registered as female.
In the end, this means that the woman is also technically her own child’s uncle. Try to wrap your head around that.
Chimeras on the Rise
Although human chimeras are considered rare, they may not actually be all that uncommon. Some scientists estimate that up to every 10th person might have some degree of chimerism.
The reason is simple. In most cases, chimerism doesn’t cause any physical or other abnormalities, so no one ever notices it.
“Since many chimeras appear normal and may not show functional impairments of reproduction, most human chimeras go undetected,” explained Wenk.
There are some cases where chimerism can result in an intersex condition, resulting in the person developing parts of both female and male anatomy. That, however, is exceedingly unusual, said Wenk.
It may also be that the number of chimeras is growing. This is due to the rising number of babies born through in vitro fertilization.
To maximize the chances of fertilization, many fertility treatments implant more than one embryo in a mother. As a result, the chances of the embryos merging in the womb also increase.
Although chimerism is most of the time physically harmless, it may cause legal issues. For example, in 2006, a chimeric woman from Washington nearly lost custody of her children because DNA tests suggested she was not their mother.
All because she carried another’s DNA in her.
Fortunately for the woman from our story, she got the situation cleared without problems. And now she can tell her children an unbelievable story of their vanished uncle.