Unions with sisters, or probably, in most cases, half-sisters, occur in the royal families of Baghirmi,[1705] Siam,[1706] Burma,[1707] Ceylon,[1708] and Polynesia.[1709] In the Sandwich Islands, brothers and sisters of the reigning family intermarried, but this incestuous intercourse was in other cases contrary to the customs, habits, and feelings of the people.[1710] And, in Iboína of Madagascar, where the kings were occasionally united with their sisters, such marriages were preceded by a ceremony in which the woman was sprinkled with consecrated water, and prayers were recited asking for her happiness and fecundity, as if there was a fear that the union might call down divine anger upon the parties.[1711] Cambyses and other Persian kings married their sisters,[1712] and so did the Ptolemies of Egypt.[1713] According to Sir Gardner Wilkinson, it is not only noticed by Diodorus, but is fully authenticated by the inscriptions both of Upper and Lower Egypt, that the same custom was in force among the Egyptians, from the earliest times;[1714] but, except in the case of the Ptolemies, I have seen no clear evidence that marriage took place between brothers and sisters who had both the same father and the same mother. Garcilasso de la Vega states that the Incas of Peru, from the first, established it as a very stringent law that the heir to the kingdom should marry his eldest sister, legitimate both on the side of the father and on that of the mother;[1715] whereas, according to Acosta and Ondegardo, it had always been held unlawful by the Peruvians to contract marriage in the first degree, until Tupac Inca Yupanqui, at the close of the fifteenth century, married his sister on the fathers side, and decreed “that the Incas might marry with their sisters by the father’s side, and no other.”[1716]