The personal affiliations that exemplify these considerations, and that therefore suggest some relevant limitations on the relationships that might be entitled to this sort of constitutional protection, are those that attend the creation and sustenance of a family — marriage, e. g., Zablocki v. Redhail, supra; childbirth, e. g., Carey v. Population Services International, supra; the raising and education of children, e. g., Smith v. Organization of Foster Families, supra; and cohabitation with one's relatives, e. g., Moore v. East Cleveland, supra. Family relationships, by their nature, involve deep attachments and commitments to the necessarily few other individuals with whom one shares not only a special community of thoughts, experiences, and beliefs but also distinctively personal aspects of one's life. Among other things, therefore, they are distinguished by such attributes as relative smallness, a high degree of selectivity in decisions to begin and maintain the affiliation, and seclusion from others in critical aspects of the relationship. As a general matter, only relationships with these sorts of qualities are likely to reflect the considerations that have led to an understanding of freedom of association as an intrinsic element of personal liberty. Conversely, an association lacking these qualities — such as a large business enterprise — seems remote from the concerns giving rise to this constitutional protection. Accordingly, the Constitution undoubtedly imposes constraints on the State's power to control the selection of one's spouse that would not apply to regulations affecting the choice of one's fellow employees.
