Lydia Fairchild was a proud mother who faced the most unusual of challenges. She had to fight in court to prove the children born from her body were her own. "I knew that I carried them, and I knew that I delivered them. There was no doubt in my mind," Fairchild said....

Fairchild's fight for her kids began when she was 26-years-old, unemployed and applying for public assistance in Washington state. Everyone in her family had to be tested to prove they were all related.

The Department of Social Services called Fairchild and told her to come in immediately. What Fairchild thought was a routine meeting with a social worker turned into an interrogation. The proud mother was suddenly a criminal suspect.

There Must Be an Explanation

"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?'" Fairchild said. The DNA test results challenged everything she knew about her family. Yes, her boyfriend was the father of the children, and, yes, they were all related, according to the DNA, except for Fairchild. She was told she wasn't the mother.

Fairchild was certain a mistake must have been made, but she recalled a social worker saying to her, "Nope. DNA is 100 percent foolproof and it doesn't lie."

It's a rare condition called chimerism, with only 30 documented cases worldwide.

Chimerism can be detected in DNA testing. The Lydia Fairchild case, for example, was brought to court after DNA testing showed that her children could not be hers, since DNA didn't match. The charge against her was dismissed when it became clear that Lydia was a chimera, with the matching DNA being found in her cervical tissue.