Sarah Boseley: Twins and the Tabloid: What is It About Conjoined Twins That So Fascinates Us?

What is it about the idea of conjoined twins that so fascinates people? The original Siamese twins, Chang and Eng, who shared a liver, made a living in Victorian times by parading themselves for the public in America and Britain. Although they had enough money to retire to the greater dignity of a farm in North Carolina, they remained a curiosity, and a metaphor for the United States - E pluribus unum, one and united.

The life and death drama of Natasha and Courtney Smith, from St Albans, Hertfordshire, has been paraded in the papers in intimate detail since February, after their dad and 24-week pregnant mum sold exclusive rights to their story to the Sun.

Yes - to leap in ahead of any accusations of hypocrisy - the Guardian ran stories about them too. So we did last year about the Maltese twins, when their Catholic parents opposed the separation and a court ruled against them. Originally it seemed as though the case of Natasha and Courtney might raise similar issues. But in fact the two stories could hardly be more different.

In the Maltese case, the parents arrived in the UK for the birth. They did not want them separated because it would mean seeking the death of one to save the other. Their supporters included pro-life groups and medical ethicists who felt parental rights were being overridden.

It must have been the hardest few months of the parents' lives. They behaved with great dignity. The court ruled against them, and at the eleventh hour, rather than appeal, they agreed that the operation should go ahead. Although newspapers wrote screeds about the ethics of the decision and the complexity of the operation, the family enjoyed as much privacy as possible in the circumstances. Nobody knew their identity or was allowed to intrude into their feelings.

Rina and Michael Attard did eventually go public. In June last year, when the worst was over and Jodie was recovering in a Manchester hospital, they agreed to exclusive interviews and pictures of the baby with the Mail on Sunday, the News of the World and Granada TV, in return for a six-figure sum. The money went into a trust fund for the surviving twin - revealed as Gracie - who would need further expensive medical treatment.

And then we have Natasha and Courtney Smith. In November last year, just five months after the Attards sold their story, Tina May and her partner Dennis Smith were told after a routine scan at 14 weeks that the twins she was carrying had one heart between them.

Doctors at Queen Charlotte's hospital, which then took over management of the pregnancy, insist they kept the parents fully informed throughout. At 20 weeks, shortly before the deal with the Sun, Lewis Spitz, the world expert in separating conjoined twins, became involved. Dr Spitz, based at Great Ormond Street, knows better than anyone that no twin born sharing a heart has survived separation. Indeed, in 1986, 1989 and in 1994, he had made the tough decision not even to try to operate on twins who shared a heart - and they had died.

Ms May and Mr Smith, who refused a termination, would have been told more than once that it would take a medical miracle to keep either twin alive. At 30 weeks, it was clear the heart was seriously abnormal, with not only a large hole but crossed arteries. Tests soon after the birth confirmed the doctors' fears. The parents would have been told there was no hope unless the twins survived a month - regarded as highly unlikely.

It is almost too agonising to contemplate, and yet the parents have lived through the last months in the full-on glare of the Sun. In February, it ran pages of exclusive, in-depth probing of their distressing circumstances. There was more of the same shortly before the birth. Then there was the birth itself. Each time it was packaged as another Attard dilemma - that Courtney must die to save Natasha. Only once did the Sun nod towards the greater truth, which was that it was possible both babies would die.

Maybe Ms May and Mr Smith have sufficient inner strength to deal with the enormity of their tragedy and that sort of newspaper exposure at the same time. But you cannot help wondering whether they felt able to discuss and grieve freely over their predicament with the Sun at their elbow. Was it worth the money?

Great Ormond Street hospital sought and won a court injunction to keep the press out the moment the babies were turned over to them. The hospital said it wanted to protect the staff and the babies. Perhaps it was just as much to protect the parents.

sarah.boseley@guardian.co.uk