In 1895, surgeon J. W. Ballantyne considered the case of the Biddenden Maids from a teratological perspective. He suggested that they had in fact been pygopagus (twins joined at the pelvis). Pygopagus twins are known to put their arms around each other's shoulders when walking, and Ballantyne suggested that this accounted for their apparently being joined at the shoulders in drawings. The pygopagus Millie and Christine McCoy had lived in Britain for a short time before going on to a successful singing career in the United States, and it was known from their case that such twins were capable of surviving to adulthood.
