It’s a phrase that became ubiquitous with daytime television in the 1990s. “You are not the father.”
But what happens when the test comes back showing, contrary to our understanding of how baby making happens, that the mother isn’t the mother?
Today’s Moment of Science… Chimerism and the curious case of Lydia Fairchild.
In Greek mythology, Chimera was the offspring of Typhoeus and Echidna, a fire breathing dragon and a half-woman, half-snake respectively. The beast was a three headed creature with a lion’s head attached to the body of a goat with a serpent caboose. It could breathe fire, and we haven’t yet ruled out its existence somewhere today in the bowels of Australia.
Ancient mythical incest aside, the reality of chimerism is a bit more like biological ‘whoopsiedoodle.’ To piece together a new human, after all the sweating, panting, and apologizing, two sets of chromosomes smash into each other forming the blueprints for one unique and precious little tax break. Every once in a while after fraternal zygotes have just started incubating, for no apparent reason, they’ll merge into one organism.
This is tetragametic chimerism, meaning the offspring has chromosomes from two eggs and two sperm. There are other types of chimerism that also result in getting just a dash of spicy DNA, but this is the form commonly referred to as “eating your twin in the womb.”
A recognizable sign of chimerism is heterochromia, marked by a visible difference in pigmentation on the right and left sides of the body. This can affect any combination of the hair, skin, or eyes. However, not everyone with two eye colors is a chimera, and there aren’t believed to be visible signs in most cases of tetragametic chimerism.
Due to the rarity of the condition and the molecular level you have to dig through for confirmation, you could carry your lazy twin’s ass around for decades before you get a diagnosis. Autoimmune issues and infertility are a few known complications for people dealing with chimerism.
In the case of Lydia Fairchild, she was pregnant with her third baby in 2002 and her health was just fine. She was having financial problems as a single mother and applied for state assistance. As a matter of protocol, a DNA test was ordered for both her and the father to make sure these were their kids. Indeed, the father was the father.
But test after re-test after re-test showed that Lydia was not their mother.
The state threw accusations of welfare fraud or a “surrogacy scam” at Fairchild. Her doctor even agreed to testify that he’d seen her pop out the first two but apparently it wouldn’t be enough in the face of DNA evidence. Attorneys kept turning her case down. She was threatened with having her children taken away by the state.
Across the country, another woman had a similar problem. Karen Keegan needed a kidney transplant and her family got tested to find a match. In the course of testing, two out of three of the children she’d definitely birthed weren’t hers genetically. This compelled researchers to ask if they could poke at her a bit after she healed up from the kidney transplant. After getting a scrape of cells from just about everywhere, they were satisfied that Keegan was a chimera with two distinct sets of DNA, and indeed the mother of all her children.
So around the time that case study was published, Fairchild was giving birth to her third child with an officer of the court present in the delivery room to administer a DNA test. When the results came back declaring she wasn’t the mother of a kid she was still healing from delivering, finally a lawyer was like “that’s suspicious” and took on her case. Attorney Alan Tindell stumbled across the Keegan article, and everything turned around.
He asked for more DNA testing from Fairchild and her family members. Her mother’s DNA matched to the degree you’d expect a grandmother’s to match. So it was of little surprise when Fairchild’s cervical DNA was a match, showing she was a chimera, and indeed the mother of her children.
Her case was dismissed, with an apology from the judge and approval for the financial assistance she initially applied for.
This has been your Moment of Science, reminding you that there is no such thing as foolproof technology as long as you think you can’t be fooled.
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