Is it possible to raise a stranger’s child as one’s own? And is it wise? These are the fundamental questions Barbara Melosh probes in Strangers and Kin, her provocative history of U.S. adoption over the past century. A professor of English and history at George Mason University and an adoptive mother herself, Melosh uses adoption as a lens for examining “our received truths about family, identity, and kinship.”

In the early twentieth century, theories of eugenics fed fears of the “bad seed” and led to extensive observation and testing of children before they were deemed adoptable. Unwed mothers were seen as “fallen women” whose sinful nature might be inherited. As a result, children spent years in foster care and orphanages before they were finally placed in families. By the 1950s women who gave birth out of wedlock were judged less harshly, but the consensus was still that “girls in trouble” should give up their babies and start anew. Social workers recognized the psychological benefits of placing infants as young as possible, but adoptions remained confidential, “closed” affairs, and social workers aimed to match babies and parents in as seamless a manner as possible—creating families that looked “as-if-begotten.” Melosh describes a cult of domesticity in which social workers believed it was in every child’s best interest to grow up in a two-parent family, and the stigma of infertility seems to have been surpassed only by the scarlet letter of illegitimacy.

Seen as “the best solution” to the problems of unwed motherhood and infertility throughout the 1940s and 1950s, adoption peaked in 1970, when U.S. families adopted 89,000 unrelated children (this excludes stepchildren and biological relatives). Five years later, though, the number of stranger adoptions had dropped to 48,000—a level that Melosh says has remained constant ever since.

What changed, she argues, were the political and scientific beliefs that influence Americans’ attitudes toward adoption. Describing adoption as “a case history of the shifting boundaries of American pluralism,” Melosh writes: “In the 1970s and 1980s, critics across the political spectrum—from those who identified with black nationalism, anti-imperialism, and feminism to those who espoused sociobiology—challenged the wisdom of stranger adoption.”

Feminism and liberal views of sexuality eroded the stigma attached to unwed motherhood, and black nationalism challenged the wisdom of adoption across races. In 1972 the National Association of Black Social Workers denounced placing African-American children with whites as “a form of genocide.” Rights movements emerged to press the twin causes of birth mothers, who felt they’d been forced to give up their babies, and adoptees, who felt their identity had been stolen. One result has been a push for states to open sealed records so adoptees and birth mothers can be reunited. Another has been the open adoption movement, in which birth mothers select their babies’ adoptive parents and maintain varying degrees of contact after adoption. As the number of available infants in the United States has dwindled, increasing numbers of Americans have adopted abroad, creating families that are often visibly multiracial.

All this has transformed adoption and broadened our conception of the family, says Melosh. Although adoption has come under attack from various quarters through the years, she finds hope both in recent federal legislation to support adoption and in changing norms within the practice itself. “Adoptive families,” she writes, “might now be seen to represent not the families we never were—the ‘archaic and nostalgic’ ideal of post-war domesticity—but instead the families that we are becoming—diverse, flexible, multicultural.”

Adoption has the potential to be more than merely a substitute for biological parenthood. It challenges us, Melosh proposes, to turn from the pain and loneliness of the postmodern quest for self and identity, and to take up a much older question—Who is my neighbor?—and the far richer quest for kinship.