They’re called Siamese twins because of two specific brothers, Chang and Eng Bunker, who were born physically connected in Siam (now Thailand) in 1811. The brothers became so famous during their decades of public appearances across Europe and America that their nationality became shorthand for the condition itself. By the 1830s, any set of conjoined twins was referred to as “Siamese twins,” and the label stuck for over a century.
Chang and Eng Bunker: The Original Pair
Chang and Eng were born on May 11, 1811, in Meklong, Siam, to a Chinese-born fisherman named Ti-eye and his wife Nok. They were joined at the chest by a band of tissue that connected their livers through shared blood vessels. The couple had seven other children, none of whom were conjoined.
In 1829, when the brothers were 18, they were brought from Siam to the West and put on display for audiences hungry for novelty. For over a decade they appeared before royalty, medical specialists, and paying crowds across Europe and the Americas. They became household names, and their fame was so total that their birthplace became permanently linked to their condition. Promoters billed them simply as “The Siamese Twins,” and the phrase entered everyday English.
Fame, Barnum, and Life in America
Nineteenth-century America had an enormous appetite for spectacle, and the Bunker brothers landed right in the middle of it. Carnival culture and so-called “freak shows” were mainstream entertainment, and conjoined twins from an exotic country were a guaranteed draw. The brothers eventually toured England with P.T. Barnum, though by most accounts they couldn’t stand him. Still, the partnership cemented their celebrity.
Chang and Eng eventually settled in North Carolina, became U.S. citizens, married sisters Adelaide and Sarah Yates, and fathered a combined 21 children. They owned land, farmed, and lived relatively ordinary lives between their touring seasons. Their story was remarkable not just for their physical connection but for how fully they built independent identities within American society.
Why the Medical World Dropped the Term
Today, doctors and medical literature use “conjoined twins” instead of “Siamese twins.” The shift happened gradually over the twentieth century as the medical community recognized that tying a condition to a nationality was both inaccurate and culturally insensitive. Conjoined twins occur in every population worldwide, at a rate of roughly 1.5 per 100,000 births, with a 2-to-1 female predominance. The condition has nothing to do with Siam or Thailand.
“Conjoined twins” is also more descriptively useful. It points to the actual biology: twins whose bodies are physically fused because a single fertilized egg began to split into identical twins but didn’t fully separate. “Siamese twins” tells you nothing about the condition and everything about one famous case from the 1800s.
What Connected Chang and Eng
The brothers were joined at the lower chest by a flexible band of flesh, a type of connection now classified as thoracopagus (joined at the chest area). Inside that band ran shared blood vessels connecting their livers. During their lifetimes, doctors debated whether separation surgery was possible, and Chang and Eng themselves occasionally considered it.
The question was answered after their deaths. Chang died first, on January 17, 1874, likely from a blood clot in his brain. Eng woke to find his brother dead and died himself within hours. An autopsy conducted at the Mütter Museum in Philadelphia over two days revealed that the shared liver vessels would have made separation extremely dangerous with the surgical tools available at the time. A 19th-century surgeon almost certainly could not have separated them without killing at least one brother.
Why the Old Name Persists
Despite the medical shift to “conjoined twins,” many people still search for and use “Siamese twins” because the phrase was embedded in English for more than 150 years. It appeared in dictionaries, news coverage, novels, and casual conversation long before anyone questioned it. Chang and Eng were simply that famous. Their story was retold so often, and their nickname repeated so widely, that it outlasted the country name it came from. Siam became Thailand in 1939, but the phrase kept circulating.
The persistence of the term is a reminder of how powerfully a single story can shape language. Conjoined twins had been documented for centuries before Chang and Eng, going back to medieval records and earlier. But none of those earlier cases had a decades-long publicity machine behind them, touring schedules across two continents, and a connection to one of the greatest showmen in American history. The Bunker brothers didn’t just popularize awareness of conjoined twins. They gave the condition a name that, for better or worse, the world is still trying to retire.