http://news.bbc.co.uk/1/hi/uk/7182817.stm

"A pair of twins who were adopted by separate families as babies got
married without knowing they were brother and sister, a peer told the
House of Lords.

A court annulled the British couple's union after they discovered
their true relationship, Lord Alton said.

The peer - who was told of the case by a High Court judge 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.

'Truth will out'

The 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."

He told the BBC News website that their story raises the wider issue
of the importance of strengthening the rights of children to know the
identities of their biological parents.

"If you start trying to conceal someone's identity, sooner or later
the truth will out," he said.

"And 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.

'Incredibly rare'

"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.

Today, however, adopted children grow up with a greater knowledge of
their birth families - and organisations try to place brothers and
sisters together.

If that were not possible, the siblings would still have some form of
contact with each other.

"This sad case illustrates why, over the last 20-30 years, the shift
to openness in adoption was so important," Ms O'Reilly added."