World famous conjoined twins fathered 21 children during their lifetime

A pair of conjoined twins, who were born in 1811, fathered 21 children in their lifetime.

Chang and Eng were born in Thailand, which was called Siam at the time.

The pair are the origin of the old term 'Siamese twins' which has been used to describe conjoined twins.

According to the Guinness Book of World Records, their mom may have sold the twins into slavery.

During the 19th century, and up until the mid 20th in some parts of Europe, one kind of attraction involved guests going to gawk at people.

Over the many decades the practice continued it is documented to have included people with a visible physical disability such as Chang and Eng.

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The twins met with the King of Siam before travelling round the globe for some ten years, visiting the US, Canada, Cuba and Europe.

When they turned 21, the twins reportedly managed to take over control of the business they were the main feature of, and came into a lot of money.

Ultimately, they settled down in Mount Airy, North Carolina, where they bought a farm for themselves to live on.

They were offered surgery to separate them, but declined.

The pair were attached together by a small band of flesh, and an autopsy revealed that their livers were also joined.

After settling in North Carolina, Chang and Eng married sisters Adelaide and Sarah Yates.

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They became naturalized citizens in the US, and adopted the surname Bunker.

In an attempt to maintain some privacy for their spouses they had separate homes from each other.

During their lives together they also had 21 children with their spouses, this is the most fathered by a pair of conjoined twins. Chang and Adelaide are said to have had 10, while Eng and Sarah reportedly had 11.

Guinness Book of World Records Editor-in-Chief Craig Glenday said: "With Chang and Eng it was never really documented how they conducted themselves in a sexually intimate way, but it is interesting to note that when the wives had their children, they delivered only maybe four or five days apart, which suggests some kind of coordination."

They also visited their spouses on a three-day long rotation, allowing them to spend equal amounts of time together.

Slavery was also still legal in North Carolina when the twins were alive, and they are documented to have owned slaves.

They died on the same night on January 17, 1874, aged 63, with Chang passing away first, shortly followed by Eng.