The National Socialists defined Jews on racial rather than on religious grounds and used the number of Jewish parents and grandparents to determine 'how Jewish' the person was. Also see Nuremberg racial laws.
According to the Nazi definition, 'full Jews' were persons with three or four Jewish grandparents and persons with two Jewish grandparents who either had a Jewish spouse or belonged to a Jewish community. 'Half Jews' were persons with two Jewish grandparents who did not belong to a Jewish community and did not have a Jewish spouse. 'Quarter Jews' had one Jewish grandparent.
This definition labelled people as 'Jews' who had never regarded themselves or wanted to be regarded as such in the Netherlands before the war. Especially the last two categories comprised people who had never had any religious or cultural involvement with Judaism and therefore did not consider themselves Jews. Even some people in the first category had such an assimilated lifestyle that they would not have described themselves as Jews.