Taking control: Chang (left) and Eng Bunker become slave-owning Southern gentlemen

The walls in Chang and Eng Bunker’s bedroom would have had some tales to tell, if walls could talk. Their marital bed was built for four — brothers Chang and Eng in the middle and their wives on either side. Between them, they conceived some 21 children in that bed.

For Chang and Eng were the original Siamese Twins, conjoined siblings who provided the name for all who suffer this accident of birth.

As a new biography reveals, the pair triumphed over extraordinary odds and appalling prejudice in 19th-century America and Britain. Brought to the West to be exhibited as freaks and probed by doctors, the enterprising Bunkers eventually became rich Southern gentlemen and plantation owners.

But, says U.S. academic Joseph Orser in The Lives of Chang and Eng, the pair were never allowed to forget that many considered them ‘monsters’ whose sexual urges and desire to pursue a normal family life were unnatural, even devilish, abominations.

Born in 1811 in a fishing village 60 miles from Bangkok, the twins really had their roots more in China than in Siam, later renamed Thailand. Their father was a Chinese fisherman and their 35-year-old mother was half-Chinese, half-Malay.

The two midwives who helped at the birth recoiled in superstitious horror at the thick ligament connecting the babies just above their waists. The twins’ mother probably saved their lives by untwisting the ligament — which had been connected to a single umbilical cord — and moving the babies so they lay staring into each other’s eyes. She named them In and Jun (anglicised to Eng and Chang). Chang — on the left — was always slightly shorter and the upper half of his body arched away from his brother.

Their mother encouraged the boys to exercise, stretching their connecting ligament so that it gradually grew to more than five inches — enough for them to run, swim and handle a boat. Crucially, they were able to bow 18 times, as custom dictated, when they were presented to the king of Siam, Rama III.

Their life, helping their family to sell preserved ducks’ eggs, might have passed in obscurity had they not been spotted by a British merchant when they were adolescents.

Robert Hunter at first thought the twins were ‘some strange animal’ when he saw them swimming in a river. But he recognised their commercial potential and easily persuaded their impoverished family that the twins should accompany him back to the West and be exhibited as a public curiosity. They agreed but the king, who wanted to show them off at court, was reluctant.

Scroll down for video

It took five years and the help of an American sea captain, Abel Coffin, to win over the king, who was bribed with a telescope and a troupe of temple dancers. The twins’ mother — whose husband had died when the boys were young — received $500 (£300) for contracting her sons to Hunter and Coffin for 30 months.

On board Captain Coffin’s ship as they sailed for Massachusetts with a translator in 1829, the 17-year-old twins showed that they were bright and extremely co-ordinated. They quickly picked up the rudiments of English and could scurry up the mast as fast as any sailor aboard.

In Boston they were exhibited as The Siamese Double Boys and were an immediate sensation.

In theatres and halls across the U.S. they performed for four hours a day, six days a week, entertaining thousands with somersaults, backflips, an uncanny ability at draughts and chess, and their prodigious strength — they could carry a 20-stone man.

Although Captain Coffin told some people that he and Hunter ‘owned’ the boys, the twins were actually paid well for their hard work.

Defying the gossips: The Bunker twins (pictured back centre) with their wives and two of their sons

Not many conjoined twins had survived for more than a few days, so doctors and scientists clamoured to see them too.

It suited their promoters that they were examined, albeit often invasively, by some of America’s finest doctors. Those doctors’ conclusion — that women and children could view them safely ‘without harm or offence’ — was perfect titillation to include on the show’s advertising posters.

Britain hankered to see them too, and the twins sailed there in 1830. In London, some of the world’s leading physicians were waiting to examine them. At 5ft 2in tall, the twins were now fully grown and their connecting ligament was about the size and roundness of a child’s arm.

Each one appeared to sense when the other was tickled or ate an unpleasant-tasting food, but he couldn’t hear a whisper in the other’s ear or feel a pinch on his arm. Although both were clearly intelligent, the hardier Chang was dominant and Eng would rarely speak out of turn.

The big question nagging the doctors — could the twins be separated and survive? — was something on which they couldn’t agree.

Of one thing Sir Astley Cooper, the ‘Great Lion of British Surgery’, was sure. ‘Depend on it, those boys will fetch a vast deal more money while they are together than when they are separate,’ he said. ‘Why separate them? The boys seem perfectly happy as they are.’ But that was not always to be.

The pair went on to tour the Continent and returned to the U.S. in 1831, aged 20 years old, healthier, more educated and richer.

We are making love pretty fast The twins, aged 31

Dispensing with Coffin and Hunter and hiring their own manager, they now insisted on being treated with respect. They were not above getting into fights with those who slighted them, especially anyone who suggested that their mother had sold them into slavery.

They might sound like the cruelly mistreated ‘Elephant Man’, but the pair were natural showmen who realised that their deformity was a path to a fortune. They spent the next seven years on the road, including three-month stints at the Museum of Curiosities in New York.

There they met and befriended James Calloway, a young doctor from Wilkesboro, a remote township in North Carolina. By this time the twins were tired of being continually stared at, even for money, and hankered for a quiet life. They accepted Calloway’s invitation to return home with him.

North Carolina was a slave state but under U.S. law, the twins counted as white. They became U.S. citizens, realising only when they got to the naturalisation office that they had no surname. They borrowed ‘Bunker’ from the man standing behind them in the queue.

Canny and industrious businessmen, they opened a store and, buying 200 acres, branched into farming and built a spacious home for themselves. The twins who had been leased out as teenagers themselves became slave-owners, buying dozens to work their new plantation.

But their thoughts turned increasingly to fulfilling more physical needs. Observers had long noticed that the pair loved discussing attractive women together, yet the outside world dismissed the idea that they could have a sex life as a joke.

Newspapers for years ran speculative stories about them and various women. A London woman claimed she had fallen madly in love with them but could not offer herself in marriage for fear of committing bigamy. There was similar sniggering over an American admirer who fell in love with Chang but realised a ‘divorce’ from Eng was out of the question.

When they were born in 1811 in a fishing village 60 miles from Bangkok, the two midwives recoiled in superstitious horror at the thick ligament connecting the babies just above their waists

There was even a joke that Chang had interfered in a ‘love intrigue’ of Eng’s: the brothers wanted to fight a duel over it but couldn’t agree on a distance from which to shoot at each other.

The twins were undeterred by the mockery. ‘We enjoy ourselves pretty well but have not as yet married,’ they wrote, aged 31, to Robert Hunter, the man who had ‘discovered’ them. ‘But we are making love pretty fast and if we get a couple of nice wives we will be sure to let you know about it.’

In fact they were pursuing the daughters of a neighbouring farmer, David Yates. An unusual romantic conundrum had arisen.

Over several years, Chang and the slimmer, more attractive sister, Adelaide, had fallen in love. Eng and her sister, Sarah, had not.

Marrying two sisters made sense, however, as Victorian propriety would not have tolerated a woman sharing such intimacy with any other female.

It took the somewhat portly Sarah five years to agree to Eng’s entreaties, but both couples were married by a Baptist preacher in Yates’s living room in 1843. The foursome then returned chez Bunker, where the marital bed had been enlarged and strengthened.

The twins advertised their last appearance

Quite how they all envisaged their marriage working is not clear but, according to some reports, the twins had considered drastic measures.

Despite being warned by various doctors over the years that an operation to separate them could prove fatal, they had travelled to Philadelphia a few months before their wedding for just that purpose. They were waiting to go into surgery when the sisters, who had learnt of their quest, burst in and persuaded them not to go through with such a risky procedure.

Nonetheless, the wedding provoked a national scandal, with accusations that the marriage was ‘bestial’.

When both wives rapidly produced daughters — proving that these were not platonic relationships — the outrage reached fever pitch. Abolitionists in the North blamed the ‘depravity’ on a Southern culture perverted by the ‘sin of slavery’.

‘The prospect of the twins engaging in sexual relations with women disturbed sensibilities,’ says Oser, their biographer. When a Kentucky woman gave birth to stillborn conjoined twins, she blamed seeing pictures of the Bunkers at around the time she conceived.

Still, the brothers went on to father 21 children — 11 by Eng and ten by Chang.

The couples’ bedroom etiquette remains unclear. It was certainly not considered a polite topic at the time, although a local newspaper noted that their wives’ first children were born just six days apart in 1844. A later pair were separated by eight days.

Amid reports that the wives — who must have shown amazing forbearance over the years — finally began to argue, the twins set up separate homes and installed a wife and children in each. They agreed to split each week between the two.

But while the families might seem to have had all the trappings of gentry, with their estates, slaves and silverware, money was sometimes tight — especially after the South was ruined in the American Civil War.

So the brothers had to go back ‘on tour’ six times in later life, sometimes taking their children (none of whom was physically deformed, though two were deaf). It must have been humiliating, especially when — in their 50s — they signed up in New York with the infamous freak show proprietor P.T. Barnum.

The Prince of Wales was among guests who watched them perform alongside the midget General Tom Thumb, the Bearded Lady and the tiny-headed Zip the Man Monkey.

In 1868 they returned to Britain. The twins had fond memories of the country, but the public mood had turned against freak shows. Reporters doubted that their children could actually be theirs. ‘For some, it was too “disgusting” to imagine these “human monsters” as husbands or fathers,’ says Orser.

Meanwhile, the twins found they were cramping each other’s style: Eng loved all-night poker, Chang’s weakness was boozing.

In 1870, as they were returning from a tour of Europe and Russia, Chang suffered a stroke down the side closest to his brother. Eng nursed him as best he could, carrying around Chang’s now useless leg in a sling as his ailing brother leant on a crutch.

In January 1874, when the twins were 62, Chang caught bronchitis but still insisted that they venture out in the cold to honour their twice-weekly house-moving ritual. Two days later, Eng awoke early and called for help. His brother had died.

‘Then I am going!’ cried Eng, and began twisting in panic in bed. Sweating profusely and saying that he was in great pain, he told his wife: ‘I am dying.’ Drawing his brother to him, he uttered his final words: ‘May the Lord have mercy on my soul!’

By the time the doctor arrived, ready to cut the twins apart, Eng was dead, just two-and-a-half hours after his brother passed away.

A post-mortem examination, conducted by doctors who described the twins as ‘the monster now before us’, showed that Chang may have had a cerebral clot but Eng appeared literally to have died of fright, overcome by the realisation that he was attached to a dead man.

Even in death, the twins provided a spectacle when the post-mortem results were made public. Finally, doctors were able to discover just how connected the twins were.

Not only did they share a liver, it transpired, but the make-up of their connecting ligament was so complex that they would never have survived being parted.