A couple discovered after they had married that they were twins who had been split up at birth and adopted by separate families, according to a member of Britain's House of Lords.
British peer David Alton recounted the story to parliament last month to support his argument that artificially conceived children should be told who their biological parents are.
Alton said he had heard the story of the separated twins from a High Court judge who had dealt with the case.
"This did not involve in vitro fertilization: It involved the normal birth of twins who were separated at birth and adopted by separate parents," said Alton, an independent member of the Lords. "They were never told that they were twins."
"They met later in life and felt an inevitable attraction, and the judge had to deal with the consequences of the marriage that they entered into and all the issues of their separation," he said.
"I suspect that it will be a matter of litigation in the future if we do not make information of this kind available to children who have been donor-conceived," he said.
Alton could not immediately be reached for comment and no further information was available about the twins or where they were from.
"I think it's a very tragic story for the people involved," said Pam Hodgkins, head of a group that helps adults affected by adoption.
"It is a lesson that we need to learn and apply to the situation of donor-conceived children," she told Sky News.
"Whilst ... nowadays it would be most unusual for siblings to be separated ... the risk of secrecy affecting the lives of people born as a result of egg and sperm donation is exactly the same as the risks that have affected adopted people in the past," she said.
(Reporting by Adrian Croft; Editing by Stephen Addison)