Half-siblings in love.

They met as adults:

"I know that loving my brother in this way is wrong morally and legally, but it just feels right," says 22-year-old Danielle [Heany].

"The only way to explain it is to say that the day I met Nick, I felt I had finally met my soulmate. Everything clicked. I would marry him if I could."

Nick [Cameron], 28, adds: "My feelings are very confused. We are very deeply in love with each other, but sometimes I think 'she's my little sister. I shouldn't be feeling this way.'

"All I know is that for the first time in my life I feel I belong. I should feel ashamed of it, but I don't."

But this is not a case of offspring of a popular sperm donor who learn the truth after they fall in love. These two have the same mother, and they knew they were half-siblings when they met. Their mother, Susan, meaning to make up for the lost family life, introduced them.

It was Susan who reported them to police after walking in on them making love in the autumn of 2006, and shouted in horror: "What you are doing is morally wrong."

Quite aside from the perplexities of the incest taboo, this case seems to involve some serious hostility between mother and children. Why were they having sex where their mother could walk in on them? Is she the audience for their love?

The two now face arrest if they have sex, and though they live together and act very demonstrative in public, they say they will follow the law:

"We have an unbreakable bond. Of course, it will be hard living together and there will always be temptation, but we have decided that we can still love each other without having sex.

"I love Danielle and because of that I don't want to do anything which might put her in prison, and she feels the same way about me. The sexual expression of our feelings is only one part of the relationship."

Danielle, a former hairdresser, adds: "What we can't live without is the closeness and intimacy. We can still talk, we can still go for walks, we can still love each other.

"Legally we can still kiss, still hold hands, still carry on together, we just can't have intercourse."

They may be lying, but unless they let mom walk in on them again, how can the state know?