'Thirty or 40 years ago, it would have been more likely that twinsД«e separated and brought up without knowledge of each other.'Д«ut she claimed that there was far more openness today with adopted children about their birth parents and background. Mo O'Reilly, director of child placement for the British Association for Adoption and Fostering, said such an incident was traumatic but very rare. 'And of course there is unlikely to be anyone more similar to any individual than their sibling.' But when we are unaware of that relationship, we are naturally drawn to people who are quite similar to ourselves. 'We have a resistance, a very strong incest taboo where we are aware that someone is a biological relative.

Pam Hodgkins, chief executive of the charity Adults Affected by Adoption, said there had been previous cases of separated siblings being attracted to each other.

They lost each other as babies and now they have lost each other again. 'And if you don't know you are biologically related to someone, you may become attracted to them and tragedies like this may occur.'ДЄudrey Sandbank, a family therapist and author of Twins and Triplet Psychology, said the twins are likely to have felt 'like soulmates' when they met for the first time because of their shared genes. 'If you start trying to conceal someone's identity, sooner or later the truth will out. 'This will lead to these heartbreaking situations. But you could be married by then, or have fallen in love with someone. The Government has drawn up legislation that will deny you this knowledge until you are 18. 'This means the state is colluding in a deception. He said: 'One of its provisions is to deny the child's right to know about its biological identity. The matter will be debated next week at the next reading of the controversial bill. Lord Alton and his supporters want the genetic history of a child recorded on its birth certificate. 'And I believe the Government will leave itself open to class actions in the future if it collaborates in keeping information of this kind from children who have been donor-conceived.' No other details about the couple, their relationship, or the annulment have been made public but the peer added: 'It was appalling for this couple to discover they were married to a close relative. The case came before a judge, sitting in private, in the High Court Family Division where, according to Lord Alton, 'he had to deal with the consequences of the marriage that they entered into and all the issues of their separation'. Marriages can be annulled in cases where there is a 'prohibited degree of consanguinity' - blood relationship. It was only after they married, according to Lord Alton, that they became aware of the 'appalling' truth and sought to have their union dissolved. Neither knew they had a twin and when they met as adults they did not realise they were related but felt 'an inevitable attraction'. The judge told Lord Alton that the twins had been parted at birth and adopted. '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 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.

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. A judge ruled the union was legally invalid. When the unnamed couple realised the shocking truth about their relationship, they had their marriage annulled at a secret High Court hearing. The harrowing story of twins who were separated at birth and married each other without realising they were brother and sister was revealed today.

Lost twins meme