Shock for the married couple who discovered they are twins separated at birth

The harrowing story of twins who were separated at birth and married each other without realising they were brother and sister was revealed today.

When the unnamed couple realised the shocking truth about their relationship, they had their marriage annulled at a secret High Court hearing. A judge ruled the union was legally invalid.

The couple's plight was revealed by the former Liberal Democrat MP Lord Alton, who is fighting for children to have greater rights to know the identity of their biological parents.

The peer, who raised the twins' story during a House of Lords debate on the Human Fertilisation and Embryology Bill, said: "I learned of this heartbreaking story from the High Court judge who dealt with the case.

"We were having a casual conversation about the potential problems for donor- conceived children accidentally marrying each other and he said this could also happen in naturallyconceived children."

The judge told Lord Alton that the twins had been parted at birth and adopted.

Neither knew they had a twin and when they met as adults they did not realise they were related but felt "an inevitable attraction".