Kumite according to maternal law, she is therefore the born wife of every Kroki, including her father. At least, the class organization, as we know it, does not exclude this possibility. Hence this organization either arose at a time when, in spite of all dim endeavor to limit inbreeding, sexual intercourse between parents and children was not yet regarded with any particular horror; in this case the class system would be directly evolved from a condition of unrestricted sexual relations. Or the intercourse between parents and children was already proscribed by custom, when the classes were formed; and in this case the present condition points back to the consanguine family and is the first step out of it. The latter case is the more probable. So far as I know, no mention is made of any sexual intercourse between parents and children in Australia. Even the later form of exogamy, the maternal law gens, as a rule silently presupposes that the prohibition of this intercourse was an accomplished fact at the time of its institution.
The system of two classes is not only found near Mount Gambier in South Australia, but also farther east along Darling River, and in the northeast of Queensland. It is, consequently, widespread. It excludes only marriage between brothers and sisters, between brothers' children and between sisters' children