A woman who had slept with identical twin brothers within four days of each other has been told it is impossible to identify which twin is the father of her child.
The case centers on the birth of a child, referred to as “child P,” whose birth certificate lists one of the twins as the father.
The woman, who cannot be named for legal reasons, and the other twin took the case to court, Sky News reported.
The Challenges of Identical Twins and Paternity Testing
The legal dispute reached the Court of Appeal after a family court judge initially ruled that the name of the alleged father should not be removed from the birth certificate.
The appeal panel, led by Sir Andrew McFarlane, Lady Justice King, and Lord Justice Stuart-Smith, agreed that the “truth” of the child’s paternity is that the father is one of the twins, but DNA has been unable to determine which one it is, as both men share nearly identical DNA.
Emma Hubbard, a senior associate at Hall Brown Family Law, described the case as “relatively unusual,” stating: “I certainly can’t think of another one involving the same complications,” per Daily Mail.
According to Hubbard, without a clear biological link being established, it means the child “may grow up having only a mother with parental responsibility for them”.
The Cost of Whole Genome Sequencing
Sir Andrew McFarlane explained that it is likely that science may one day be able to identify the father.
However, the cost of the testing, known as whole genome sequencing, could reach up to £90,000 (over $118K) – which puts it out of reach for the family.
“It is possible, indeed likely, that by the time P reaches maturity, it may be possible for science to identify one father and exclude the other twin, but, for the coming time, that cannot be done without very significant cost, and so her ‘truth’ is binary and not a single man,” he said.
The Potential for Future Technological Advances
The court also heard that while DNA tests are unable to settle the issue, future technological advances might make it possible.
Professor James Ware, a leading expert on genomic medicine, explained that although identical twins share almost identical DNA, they may develop small mutations after their embryo splits.
“That number can be very, very small – the average is five, but it can be up to 100 – among our three billion letters of DNA,” he pointed out.
“Those mutations will only be passed on to a child if they are contained in sperm, so analysing their sperm might help distinguish between the men, although there are no guarantees,” Ware added.
The situation has left the family with no clear answer as to which twin is the father. As the case continues, the court has ruled that the twin named on the birth certificate would no longer have parental responsibility.
“The failure to prove a fact means that that fact is not proved; it does not mean that the contrary is proved,” McFarlane said. “There is a distinction between something being not proven, and making a positive declaration that the fact asserted is not true.”
