A pair of twins who were adopted by separate families as babies got married without knowing they were brother and sister. A court annulled the British couple's union after they discovered their true relationship.
A peer - who heard of the case from a judge who was involved - said the twins felt an "inevitable attraction." He said the case showed how important it was for children to be able to find out about their biological parents.
Details of the identities of the twins involved have been kept secret, but Lord Alton said the pair did not realise they were related until after their marriage. The crossbench peer, a former Liberal Democrat MP, raised the couple's case during a House of Lords debate on the Human Fertility and Embryology Bill in December.
"They were never told that they were twins," he told the Lords. "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."
Their story raises the wider issue of the importance of strengthening the rights of children to know the identities of their biological parents. We are naturally drawn to people who are quite similar to ourselves. "If you don't know you are biologically related to someone, you may become attracted to them and tragedies like this may occur."
Pam Hodgkins, chief executive officer of the charity Adults Affected by Adoption (NORCAP), said there had been previous cases of separated siblings being attracted to each other. "We have a resistance, a very strong incest taboo where we are aware that someone is a biological relative," she said. "But when we are unaware of that relationship, we are naturally drawn to people who are quite similar to ourselves. "And of course there is unlikely to be anyone more similar to any individual than their sibling."
Mo O'Reilly, director of child placement for the British Association for Adoption and Fostering, said the situation was traumatic for the people involved, but incredibly rare. "Thirty or 40 years ago it would have been more likely that twins be separated and, brought up without knowledge of each other," she said. "This sad case illustrates why, over the last 20-30 years, the shift to openness in adoption was so important," Ms O'Reilly added.
Genetic sexual attraction is equally relevant to donor conception. In particular, it applies to my generation of donor-conceived offspring where sperm was delivered fresh to a clinic for insemination later that day and the couples going to that clinic lived in the same city. In addition, no limits were placed on the number of children created by any given donor. For example, former donors who went through DNA testing with me produced anywhere from one to hundreds of children.
Luckily the chance of this occurring today has decreased. Sperm is now frozen and shipped throughout the world, but it still is another hazard of the industry and another reason why honesty within families is so important.