The reason that conjoined twins were once called "Siamese twins" is because of Cheng and Eng Bunker, born in Siam (modern-day Thailand) in 1811. In 1829, the twins traveled to the United States and toured the country, becoming rich and famous in the process. After a decade of touring, they settled in North Carolina, where they became American citizens, bought slaves, married local sisters, and fathered 21 children.