In 2006, Lydia Fairchild’s life took an unexpected turn when a routine government assistance application transformed into a nightmare that would challenge everything she understood about biological identity. What began as a standard procedure to prove her family relationship quickly became a harrowing investigation that threatened to tear her family apart.
The DNA Dilemma
When Fairchild underwent genetic testing, the results seemed to defy logic. The Department of Social Services delivered a devastating message: the children she had given birth to and raised were not biologically related to her. In her own words, the confrontation was traumatic.
“As I sat down, they came up and shut the door, and they just went back and just started drilling me with questions like, ‘Who are you?’” she recalled.
The situation was made even more perplexing by one crucial detail: her boyfriend, the children’s father, was confirmed to be genetically related to the children. Only Fairchild appeared to be the genetic outsider in her own family.
As well as this disqualifying her from receiving financial assistance, she was now suspected of welfare fraud and was at risk of having her children taken away.
Though DNA tests are not foolproof (labs make mistakes, samples get contaminated) in this case, it was correct. A second test came back with the same, strange result. And another. And another. It began to look pretty bleak for Lydia, as the state filed a lawsuit against her for fraud.
But, her case was not unique.
In 2002, 52-year-old Karen Keegan suffered renal failure and needed a kidney transplant. When she turned to her family, she too found out that two of the three children she had given birth to and raised were her husband’s biological children, but not hers. Investigation into the cause of this would eventually help Lydia win her case against the government.
Samples were taken from all over Keegan, who they suspected of having tetragametic chimerism. Tetragametic chimerism occurs when two separate eggs are fertilized by two different sperms, and then one of the embryos absorbs the other during the early stages of development. People with this type of chimerism may have two blood types, different eye colors, or other physical signs such as birthmarks down their center.
Chimerism is rare, with only around 100 documented cases in humans. People with the condition can live with no complications from it, other than altered pigmentation. Several people have only become aware of their condition after blood tests.
In chimeric patients, the majority of cells usually end up coming from one set of DNA, Live Science reports. In some cases, the person can develop ambiguous genitalia, if the twin embryos they are developed from contain different chromosomes (ie if one twin is male and the other is female).
None of these signs were present in either Keegan or Fairchild, but after samples from all over Keegan were taken, tetragametic chimerism was found to be the cause. In Keegan’s case, the team studying her were able to discover groups of genes linking her children to her own parents.
“Because of the apparent rarity of tetragametic chimerism and the importance of the use of molecular techniques to confirm its presence, this condition may be underdiagnosed,” the team wrote in their study.
“Furthermore, if a single cell line predominates in the blood, the chimeric state may not be detected unless family studies are undertaken. Even then, the findings may be misinterpreted as ruling out maternity or paternity.”
With this knowledge, Fairchild was able to temporarily fight off claims that she was not her children’s mother, while she sought further testing.
Sure enough, a cervical swab eventually proved that she had two distinct sets of DNA: she was a chimera. Something she probably would never have known without her unusual legal problems.