Siamese Twins: How Thailand Gave a Medical Term Its Name

In 1811, in a fishing village in Samut Songkhram province, roughly 70 km from Bangkok, two boys were born joined at the chest. Their names were Chang and Eng Bunker. They lived 63 years, married two sisters, raised 21 children, and built a fortune. In doing so, they permanently attached the word 'Siam' to a global medical term.

The phrase 'Siamese twins' has nothing to do with Thai genetics. It is a historical accident: the first widely documented pair of conjoined twins simply happened to come from Siam, the name of the Kingdom of Thailand until 1939¹. The term stuck across dozens of languages and became part of everyday speech worldwide.

Today Thailand is far more than a cultural curiosity. It is one of Southeast Asia's key investment destinations, with a property market drawing capital from around the globe⁵. The link between this cultural history and the country's investment appeal is more direct than it seems: Thailand's singular identity is part of what makes it a magnet for wealthy buyers.

Key Facts

• Chang and Eng Bunker were born on 11 May 1811 in Samut Songkhram province, Siam (present-day Thailand). They were thoracopagus twins, joined at the chest¹.

• The twins toured Europe and America with a circus, later gained American citizenship, bought a plantation in North Carolina, and married sisters Adelaide and Sarah Yates. Together they had 21 children¹.

• Chang and Eng's shared liver is preserved at the Mutter Museum in Philadelphia, one of the museum's most significant medical history exhibits¹.

• Siam was renamed Thailand in 1939, but the term 'Siamese twins' survived in medical literature and everyday language worldwide.

• In 2026, villa sales in Phuket rose 12.9% year on year, with the island's west coast remaining the most liquid zone for premium investment³.

• Russian buyers remain the dominant nationality purchasing property in Phuket, while Israeli investors are increasingly active in the Koh Samui and Koh Pha Ngan markets⁵.

Story and Context

The story of Chang and Eng is not really a story about a medical anomaly. It is a story about a country that, in the early 19th century, was one of Southeast Asia's largest trading hubs. Siam was never colonized, the only country in the region that can claim that status. That independence helped create the kind of distinct cultural environment in which global phenomena could emerge.

When Scottish merchant Robert Hunter encountered the conjoined twins during a visit to Siam in 1824, he immediately spotted commercial potential. Hunter struck a deal with the family and took the boys on tour. Over the following decade, Chang and Eng travelled the world, appearing before medical societies in London, Paris, and New York. Audiences were stunned; physicians were fascinated. It was during this period that newspapers coined the term 'Siamese twins,' tying a medical description permanently to their place of birth.

Interestingly, the twins never became victims of the system that made them famous. Once they had earned significant money, they broke their contract with their manager, became naturalized American citizens, and started living as free farmers. Choosing the surname Bunker, reportedly after a New York acquaintance, symbolized a clean break from their past. Yet the word 'Siam' never left them.

For Thailand itself, the story carries a double meaning. On one hand, many Thais consider the term 'Siamese twins' outdated and somewhat uncomfortable; modern medicine prefers the neutral clinical term 'conjoined twins.' On the other hand, Chang and Eng remain among the most globally recognized people born in Siam, alongside the legendary warriors of Ayutthaya and the artisans of Sukhothai.

That historical link to world culture is part of what shapes Thailand's modern brand. A country that once exported silk, spices, and extraordinary human stories now exports something different: investment appeal. Phuket and Koh Samui are transforming from resort destinations into full-fledged international investment hubs⁵. Premium villa sales along Phuket's west coast, in Bang Tao, Layan, Kamala, and Cherngtalay, keep climbing, with branded residences proving the most resilient to market swings³.

Thailand continues to lead Southeast Asia in attracting foreign real estate capital thanks to transparent legislation, purchase structures accessible to foreigners, and strong rental yields⁴. Under Thai law, foreigners can own condominium units outright (freehold) as long as the foreign quota in a building stays under 49%, while villas and houses are typically acquired through long-term leasehold structures of 30+30+30 years[2].

Samut Songkhram, the province where Chang and Eng were born, remains a quiet corner of the country today. But the nation they made famous has become one of the most dynamic economies in Asia.

FAQ

Why are conjoined twins called 'Siamese twins'?

The term originated in the 19th century because of Chang and Eng Bunker, born in Siam (modern Thailand) in 1811. They were the first widely known and thoroughly documented pair of conjoined twins, so their nationality became attached to the condition itself¹.

Where exactly in Thailand were Chang and Eng born?

In Samut Songkhram province, about 70 km southwest of Bangkok. At the time of their birth, the country was still called Siam.

How many children did the Siamese twins have?

Chang and Eng married sisters and together fathered 21 children¹.

Is it true that their organs are kept in a museum?

Yes. The shared liver that connected Chang and Eng is preserved at the Mutter Museum in Philadelphia, United States¹.

Why was Siam renamed Thailand?

The renaming took place in 1939. The new name 'Thailand' means 'land of the free' (from the Thai word 'thai,' meaning free), underscoring the country's status as one never colonized by a foreign power.

Is the term 'Siamese twins' still used in medicine today?

Modern medical terminology favors the neutral term 'conjoined twins.' In everyday speech, however, 'Siamese twins' remains widely used across dozens of languages worldwide.

Can foreigners buy property in Thailand?

Yes. Foreigners can own condominium units freehold, provided the foreign ownership quota in the building does not exceed 49%. Villas and houses are purchased through long-term land lease structures, typically 30+30+30 years[2].

Which areas of Phuket look most promising for investment in 2026?

The west coast, covering Bang Tao, Layan, Kamala, and Cherngtalay, remains the most liquid zone thanks to a concentration of affluent buyers, international brands, and mature infrastructure³.

How much have Phuket villa sales grown?

Villa sales in Phuket rose 12.9% in 2025, with projects backed by management companies and branded residences showing the strongest resilience³.

Source: The CITY Asia

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