A member of the Ptolemy family, she is the third daughter of her father and mother, not a good position to expect the opportunity to become ruler. However, she shows her sense of leadership and determination from an early age and is named co-ruler with her father while she is still young, coming to the throne in her own right upon his death. Cleopatra breaks with the tradition of mating with a sibling or half-sibling in order to produce an heir for the throne. While this can be partly attributed to the fact that her brothers are much younger than she, she also makes it clear that she has no desire for them and that her sexual desires are important in her choice of a sexual partner.