The state does not oppose the freedom of people to express their particular cultural attachments, but nor does it nurture such expression--rather [...] it responds with 'benign neglect' [....] The members of ethnic and national groups are protected against discrimination and prejudice, and they are free to maintain whatever part of their ethnic heritage or identity they wish, consistent with the rights of others. But their efforts are purely private, and it is not the place of public agencies to attach legal identities or disabilities to cultural membership or ethnic identity. This separation of state and ethnicity precludes any legal or governmental recognition of ethnic groups, or any use of ethnic criteria in the distribution of rights, resources, and duties.