twins are one person and that they are birds: 'Their single social personality is something over and above their physical duality... It is only in certain ritual situations, and symbolically, that the unity of twins is expressed'
Turner demonstrates, via Nuer and Ndembu ethnography, that twinship constitutes a structural paradox in which physical duality and ritual unity coexist, requiring special symbolic and ceremonial mediation.
, The Ritual Process Structure and Anti-Structure, 1966thesis