"Everyone has a right to knowledge about their lineage, genealogy and identity. And if they don't, then it will lead to cases of incest," Alton told The Associated Press during a telephone interview Friday.
Alton first revealed details of the unusual case last month during a five-hour debate about a bill that would change regulations about human embryology.
"I was recently involved in a conversation with a High Court judge who was telling me of a case he had dealt with," Alton said according to a transcript of the Dec. 10 debate. "It involved the normal birth of twins who were separated at birth and adopted by separate parents.
"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."
Alton gave no additional details and would not reveal the name of the judge who told him about the case.
The High Court's Family Division declined to discuss or confirm Alton's account about the twins.
Alton, an independent legislator who works at Liverpool's John Moores University, said the siblings' inadvertent marriage raises the wider issue of the importance of strengthening the rights of children to know the identities of their biological parents, including kids who were born through in vitro fertilization.
