The fortunes of functional families began to shift in the mid-1960s as fears of the family in crisis swept the nation. The rising New Right dovetailed with a generation of politicized post-war homeowners, both of which saw formal-family zoning as a vindication of their values. For social conservatives, formal-family zoning could help stave off the decline in nuclear family formation, and for homeowners, it could protect their property values against their perception that having abnormal neighbors might drive prices down.

Neither is a persuasive reason to discriminate against functional families in zoning codes. Formal family zoning is a familiar song—the same legal mechanisms that famously reinforced housing discrimination on the basis of race, also discriminate against families that vary from the nuclear ideal of a heterosexual couple raising their biological children. There is also compelling evidence that low-density zoning, like formal family ordinances, is a significant driver of racial and class segregation. In short, formal family zoning discriminates against non-normative families, but it also reinforces the racial and economic segregation effects of low-density zoning in general.

—Kate Redburn, in “Why Are Zoning Laws Defining What Constitutes a Family?”