Moieties are two social or ritual groups into which a people is divided.
Everything in the Bininj world view is made up of two moieties, Yirridjdja and Duwa. These are two halves of a holistic world view. Everything in the world, the countryside, nature and society is known to be of one, or the other (never both).
A man and his offspring are in one of these moieties, his wife and her siblings and their father are in the other. These have strong influences over ceremonial and relational activities and interactions.
Yirridjdja and Duwa are patrimoieties, passed down from the father’s line. Some groups also have matrimoieties, which are passed down through the mother. All Bininj belong to either the Ngarradjku or Mardku matrimoiety, and these affect marriage rules.