King's wives, marriage of sisters. Though the Banyoro clans are exogamous, this rule does not apply to royalty; for in the royal family brothers frequently marry their sisters, and as there is no rule to prohibit them from having offspring, they sometimes have children by them, though princesses usually kill their children at birth. This seems to have been done rather to save trouble in nursing them than from any fear or sense of guilt. The custom of marriage with a sister is probably due to the fact that the royal family belong to some other race than the pastoral people, a race who followed the rule of succession through the female line, and the king married his sister to ensure his son succeeding him. The king had usually several princesses among his wives and often had children by them, and such children took their places with other princes as legitimate heirs to the throne, no difference being made between them and the king's sons born of women from pastoral clans. The practice of marrying a near relative was usually confined to couples of the same generation, though there was no rule which forbad a prince from marrying a princess who was either his aunt or his neice; a father, however, refrained from marrying his daughter. When a princess became a wife of the king, she did not leave him to go to some other prince, but regarded herself as his sole property.