Science discovers that a man who was never born has fathered a son.

Science is amazing.

A couple in the US, who had a paternity test after their son’s blood type didn’t match that of either parents, have been surprised to find out that the biological father of the little boy was actually his uncle.

An uncle who was never born.

Buzzfeed reports that in June 2014, the baby boy was born with the help of IVF. After he was born, the couple were told that their son’s blood type did not match either the father or his partner. Understandably disturbed, they undertook an at-home paternity test which showed that the man wasn’t actually the father of the child.

Barry Starr, a geneticist at Stanford University, told Buzzfeed that they were upset. “They thought the clinic had used the wrong sperm.”

They hired a lawyer and went to an accredited lab for a more precise paternity test, which just like the at-home test relied on the father’s cheek cells for a swab.

Again, the test came back negative for paternity.

The couple then approached the fertility clinic who said that it could not be their fault as the 34-year-old father was the only white man to donate sperm on the day their son was conceived.

So the couple decided to undergo a genetic ancestry test through Barry Starr and they were shocked at the findings: the biological father of the baby was actually his uncle — an uncle who only ever existed as a lost twin.

The man’s sperm was found to have 10 per cent of a genetic match to the infant. The genes in his sperm were different to that in his saliva meaning that the father of the boy is effectively the man’s own unborn twin.

“That was kind of a eureka moment,” said Starr. He said that then he realised they might be dealing with a chimera.

“Chimera reports are very rare but they are real.”

Chimeras occur when the DNA from a miscarried sibling is absorbed by the surviving embryo, leaving parts of its DNA in the survivor. Around one in eight pregnancies start out with multiple embryos that miscarry, most go undetected until a genetic test is performed.

Well documented chimera cases in the past include Karen Keegan from Boston who found that her blood cells had one set of genes and her ovaries held distinctly different ones. Those ovaries had produced the eggs that led to two of Keegan’s sons holding genes different from her own.

The true genetic mother was a ghost – a twin sister that she never knew and who was never born.

Another woman, 26-year-old Lydia Fairchild of Washington state found out she was her own twin and her twin was the mother of her three children in 2006 after applying for welfare payments.

The application process was relatively straightforward. It involved means and assets testing, but also a DNA test so that Fairchild could prove that her soon-to-be three kids were hers and, thus, that she was able to claim welfare payments for them. The children’s father also had to participate in the DNA test.

But when DNA tests had come back she found out while the father had parental relationship she was not their mother.

At the time Fairchild was stunned.

Fairchild told ABC News, “I knew that I carried them, and I knew that I delivered them. There was no doubt in my mind.”

Finally one of the lawyers involved stumbled on the case of Karen Keegan and realised the similarities.

Further DNA tests of Fairchild were ordered. Finally, DNA taken from a cervical smear was tested, and matched that of her children. Her twin had lived on only in the cells of her ovaries and, in essence, had gone on to mother her children. The twin’s location in her reproductive area also explained why all three of Fairchild’s children had been born without Fairchild’s DNA. (A rare occurrence for people with chimerism – only one of Keegan’s children was found to have been mothered by her twin.)

Chimera cases are notoriously rare because they are so hard to detect. BuzzFeed spoke to a geneticist who said eyes of mismatched colour and intersex conditions can be tell-tale signs of chimerism, most often there aren’t any obvious giveaways.

There are fears that chimerism may now render some DNA cases especially in forensic situations incorrect.

At the time of her case, Fairchild’s attorney Alan Tindell pointed out, “People go to death row because of DNA tests, people are released from death row because of DNA tests.”

It is thought that chimerism may become more common as more people turn to fertility clinics to help them have children, and fertility treatments lead to more multiple births.