Maternity Test Says Three Kids Do Not Match DNA
Were a mother's three kids switched at birth? Did she steal them? Or is this a genetic anomaly so rare that few have even heard of it: chimerism.
In 2002 when, out of work, pregnant, and separated from her children's father, Lydia Fairchild applied for government aid in Washington state for her three children, she got the shock of her life. DNA tests intended to confirm that she and her boyfriend Jamie Townsend were the biological parents showed that Jamie was indeed the father of the children, but Lydia wasn't their mother.
Washington Department of Social Services workers called Lydia in to their offices and began asking questions as if she was a criminal suspect. The DNA test results showed that the children and Jamie were related, but according to them, it was impossible for Lydia to be their mother.
When Lydia said she knew she'd given birth to the children, a social worker said, "Nope. DNA is 100 percent foolproof, and it doesn't lie."
Lydia Fairchild fights for her children
Lydia returned home to retrieve photos of her pregnancies, births, and the children's birth certificates. Her mother Carol said, "I thought she was joking, but she started crying." Carol said she was there when the kids were born and saw them come out. Lydia's obstetrician, Dr. Leonard Dreisbach, agreed. He volunteered to testify in court that he'd delivered the children and knew that she'd given birth to them.
But Social Services authorities still questioned that Lydia was the children's mother. More DNA tests were ordered. They returned with the same result: the children weren't Lydia's.
Not only was Lydia denied government aid for her children - she was called into family court. At risk of losing custody, she found an attorney who agreed to help, Alan Tindell.
Lydia Fairchild wasn't the only one
Meanwhile across the country in Boston, another woman heard similarly shocking news. When Karen Keegan needed a kidney transplant, her children volunteered to help. But when their blood and Karen's was tested, DNA results showed they hadn't inherited any of Karen's DNA. Karen went through a similar crisis as Lydia Fairchild: how could her own children not belong to her?
To solve the medical mystery, doctors took DNA swabs from many locations on Karen's body, including her blood, hair, and mouth. Finally, they tested tissue from a thyroid nodule that Karen had removed. The DNA from most of Karen's body didn't match her children's DNA, but the DNA from the thyroid nodule did.
Karen had a "hidden twin," also called chimerism. At some point in her early development, Karen shared her mother's uterus with another fertilized egg. The two eggs joined, and DNA from the other egg remained in parts of Karen's body, totally invisible to the eye, but able to pass itself on to Karen's children.
Saved by another human chimera
When Lydia Fairchild's attorney learned of Karen Keegan's condition, he entered the scientific report about her chimerism into Washington state's court records. Authorities witnessed Lydia's childbirth with her third child, and still questioned she was the mother until the court agreed to postpone its judgment until extensive DNA tests confirmed that Lydia, like Karen Keegan, had chimerism. "Invisible twins" inside both women's bodies were the biological mothers of the children to whom they'd given birth.
What is chimerism and how common is it?
Chimerism is a very rare condition in official medical records. Only about 100 documented cases exist. The first "human chimera" was found in 1953 when doctors discovered that a British woman had two blood types. Scientists realized that mixed blood groups with DNA from multiple births could be much more common than previously thought. A study found that one in ten twins and almost one out of five triplets could have mixed DNA in their blood, though this does not necessarily mean they are chimeras. A type of chimerism may also occur from stem cell or bone marrow transplants.
Another term for chimerism is "vanishing twin syndrome." Vanishing twin syndrome can occur in as many as 20% to 30% of multiple pregnancies. A twin that begins to develop, but dies, can be absorbed by the placenta, the mother, or a remaining twin or other multiple baby in the uterus.
Men can have chimerism, too
Karen Keegan and Lydia Fairchild aren't the only parents to have DNA tests that said they weren't the biological parents of their children. A father in Washington state who donated sperm for fertility treatments feared that the fertility clinic had used the wrong sperm after his wife gave birth. Paternity testing showed he had an uncle-nephew relationship to his son, not a father-son relationship as expected. It turned out that he, too, had chimerism, and some cells from a "hidden twin" were part of his genetic material.
It turns out that in extremely rare cases, you can be your own twin, with an invisible sibling living inside your body. It is possible to give birth to children that standard DNA tests indicate aren't biologically your own. If you are a twin or triplet, or know that your mother may have lost a twin of yours in the womb, be sure to let the laboratory know when submitting a specimen for a DNA test.
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