Millie and Christine McKoy were referred to as one person, 'Chrissie Millie McKoy' rather than two separate people.

Born into slavery, they were referred to as one person from birth. In the 19th century conjoined twins were seen as medical ‘oddities’ and ‘freaks’ and were frequently part of travelling shows. They were African American pyopagus twins, with Millie slightly smaller than Christine. They were joined at the lower spine and shared a pelvis, but each had a full set of limbs.

Chrissie Millie McKoy were sold three times between the ages of 6 months and 6 years. By 1856 they were owned by North Carolina merchant Joseph Pearson Smith, who purchased their family from the McKoys. Smith’s wife taught Chrissie Millie to read, write, speak five different languages, sing and play the piano to a high standard. They toured Europe and America, and were frequently billed as ‘The Two-Headed Nightingale’.

In 1869 the twins issued their autobiography, History and Medical Description of the Two-Headed Girl. After a thirty-year career, they retired to North Carolina where a fire in 1909, left them in financial ruin. They died of tuberculosis in 1912.