Sentence:  While a woman and a man [who are native Hawaiians] primarily establish a family, they nonetheless remain members of different "genses", and it is only as members of different "genses" that they are able to set up the family. At the same time, the children belong to the "family of their parents", but owing to the validity of their mother's side—"exclusively, to the <WSD>gens</WSD> of their mother". Thus, the members of one and the same family, the closest blood-related community, are members of two different "genses". 
Meaning of the word marked with <WSD> tags:  A tribal subgroup whose members are characterized by having the same descent, usually along the male line.