Chang and Eng Bunker were born in Siam, Thailand, and are famous for coining the term Siamese twins, referring to twins who are related to each other.
For most of its history, Thailand was known as Siam.
After the 1932 reforms, which changed the country from an absolute to a constitutional monarchy, the name was changed in 1939 to Thailand.
When it was announced that the conjoined twins Chang and Eng Bunker, better known as the 'Siamese twins', were planning to come to France in 1831, the French authorities were so fearful of the effect the then 20-year-old men would have on French women that they banned their entry into the country.
While the concept of conjoined twins, two independent people permanently joined together as one, is intriguing in many ways, few aspects arouse as much curiosity as how these two people lived their romantic and sexual lives.
According to author Joseph Andrew Orser's book, "The Lives of Chang & Eng", the Bunkers, born in Siam in 1811 and connected to the middle part of their bodies by a strip of fleshy skin several centimetres long, were spotted as teenagers by a British trader who initially thought they were "a strange animal".

"The lives of Chang and Eng:
The Siamese Twins in 19th Century America
by Joseph Andrew Orser
(UNC Press)
When they turned 18, he made a deal to bring them to America and exhibit them as public curiosities.
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A subject of study for doctors
Upon arrival, they were subjected to countless medical investigations.
A doctor, testing their junction band with needles to determine their sensitivity, found that "both boys moved away from the perforations in the middle of the band, while at 1.25 cm or more from the centre, only the twin on that side felt pain".
He also found that "when one of them tasted bitter, the other did too" and that "if you tickle one of them, the other asks for it to stop".
Questions about their love lives
But beyond their connective similarities, the public wonders about the boys' potential sex lives.
"The prospect of the twins having sex with women disturbed sensibilities," writes Orser.
"There was concern about the impact that twins being conjoined could have on women of childbearing age."
In an extreme example, when a Kentucky woman gave birth to stillborn conjoined twins, she claimed that she had seen numerous depictions of the twins in newspaper advertisements around the time she conceived her children, which affected her imagination.
Siamese twins become 'good' Americans
The brothers gained fame as monsters, and saw opportunities as Americans.
After a decade on the circus circuit, having saved some money, they retired, bought land in North Carolina and set about creating a life for themselves as Southern gentlemen.
They bought property, became American citizens and even took slaves, which is ironic considering that throughout their early lives here, many wondered if, despite their firm denials, they were not slaves themselves.
Marriage with two sisters
In 1843, Chang and Eng married the sisters Adelaide and Sarah Yates respectively, daughters of a respected local landowner.
Although the girls had 'a fair share of suitors', the brothers had got to know them over a number of years, often visiting them on their return from business trips, and befriending the whole family.
When the couples made their intention to marry known by riding together in an open carriage, a report at the time quotes how "all hell broke loose".
Some men broke the windows of the girls' father's farm and some neighbours threatened to burn his crops if he did not promise to control his daughters.
The local media reacted to the unions with mockery.
The Carolina Watchman, in an article entitled "Extraordinary Wedding", wished the wedding to be "as happy as it will be close".
Another newspaper questioned whether women should be charged for 'marrying a quadruped'.
Northern newspapers were dismayed, as abolitionist papers placed 'the blame for the union on a South contaminated by the sin of slavery'.
One newspaper even called the marriage "bestial" and described the tolerant locals as "a community whose lasciviousness is inferior to that of the Sodomites".
For their part, the two couples, and they were undoubtedly two distinct couples, moved into separate houses, the brothers alternating half-weeks in each, seeking little more than a normal life.

The Siamese Bunker with their wives, who were sisters
But many people in the public and the media, having barely managed to tolerate the existence of the brothers, feel that the concept of intimate relationships between them and 'normal' women goes too far.
Each wife gave birth to a child in 1844.
Although no details have survived of how the couples conducted their intimacy, it is interesting to note that the brothers' first children were born within six days of each other, and the next two within eight days. (They would go on to have 21 children between them).
The return to exhibitions
When the cash-strapped twins returned to the exhibition circuit, this time with two of their children, many refused to accept this unconventional family.
As they travelled around England, some members of the British press 'doubted the very existence of the 'family'', writes Orser.
"For some, it was too 'disgusting' to imagine these 'human monsters' as husbands or fathers.
The sad end of the twins
In 1870, Chang suffered a stroke that paralysed his right side, the side closest to his brother.
Eng nursed him back to relative health, while Chang slung his right leg in a sling and, using a crutch and his brother's arm, went about his daily business.
But he never regained his full health and started drinking.
A persistent cough later became vicious, and he died.
His brother, complaining of feeling ill, asked his son to check on his brother.
When told that Chang had passed away, Eng replied, "Then I'm leaving.
Over the next hour, he "suffered intense pain and distress, with cold sweat covering his body".
The only attention he paid to his dead twin was to move his body closer to him.
Two and a half hours after losing his brother, Eng Bunker died on 17 January 1874.
Source: New York Post