“All happy families are alike; each unhappy family is unhappy in its own way.” So preached Tolstoy in the first sentence of a novel that centered on the exertions, joys, and disasters attendant on family life. And while the remaining sentences in Anna Karenina—about 35,000 of them—would seem to nail the subject pretty well, that first one is spectacularly wrong, and evidence, as though it’s needed, that novelists seeking a memorable opening line should go lyrical (“Call me Ishmael” “Stately, plump Buck Mulligan etc.”) and not veer across the double yellow into oncoming sociologicese.

For it’s happy families (or even part-happy ones, such as the Bennets of Hertfordshire) who stand distinctive, each a pleasure to encounter because love and constancy—the hallmarks of any house that’s got a shot at happiness—set a foundational theme upon which mothers, fathers, brothers, sisters, visiting uncles, and live-in grandmas can string limitless variations—joyful, ironic, heartbreaking, murderous—a diverting music against the storm of one kind or another that’s always pounding the cottage roof.

Unhappy families, by contrast, are incapable of inventiveness and imagination—of hope, in a word—but live in servitude to the storm, as anyone who has been part of such a family or witness to it (or minister to it) will appreciate. How Tolstoy got it so wrong, I don’t know. Certainly he knew something about happy families (he seems to have been raised in one) and of the trials endured by unhappy families, such as the large clan he produced and abused. So perhaps it was a typesetter’s error; that he meant to say happy where he said unhappy and vice versa—and no one caught it until early reviews of bound galleys out of St. Petersburg had pronounced the opening statement “Tolstoyan” and the novel brilliant, and that was it as far as the publishers were concerned. “The readers think you’re a genius, Lev Nikolaevich. Just relax and cash the checks. No one remembers opening lines for long anyway.”

In defense of Tolstoy it needs be said that he’s far from being the only amateur (or professional) social scientist who’s failed in efforts to taxonomize family, an entity that over history has expanded, contracted, cast out, brought in, been business and love nest, fixed and nomadic, treaty- and blood-defined, village wide and townhouse narrow, male-centered and matriarch-driven (sometimes at the same time), factory and locus of consumption, war-maker and heart of pacifism, innocent and sexualized, two-parented and many-parented, the source of all children and the source of some children, a club that bestows permanent membership and one that begrudges temporary refuge. Introducing a recent issue of his eponymous quarterly that offered 85 viewpoints on the family—from ancient Egypt through contemporary Missouri—Lewis Lapham wrote he could not find a “moral” or “general rule” that tied those stories and illustrations together, but rather “proofs and demonstrations . . . attesting to the multitude of reflections in the mirror of human tragedy.” In fact, there’s only one view of the family that seems to have held true over the centuries. Like organized religion and adolescents, it’s always said to be in crisis.

The novelist Marilynne Robinson, whose view of the world is as capacious as Lapham’s is severe (though both are wise writers), made a memorable attempt to define family in an essay published in 1998 in a collection called The Death of Adam. Conceding that “family,” like a lot of other human notions, is resistant to definition, Robinson went on to posit (in her capacious way) that “one’s family are those toward whom one feels loyalty and obligation, and/or from whom one derives identity, and/or with whom one shares habits, taste, stories, customs, memories.”

Of course, while roping in families “of circumstance and affinity,” Robinson seems to offer pretty short shrift to biology. But in the very next paragraph she proposes that the “charm and genius” of the biological family lies in the randomness inherent in its arrangement, in that our blood relatives are truly thrust upon us as gifts and burdens we never asked for, and if we were pressed to determine which brothers and sisters we would choose as friends from a menu of the men and women we know (and to be cruelly fair, which of those brothers and sisters would choose us), we’d likely decline to respond. But then, like the fine Calvinist she is, Robinson plucks a wisdom lesson from these dismal contemplations, noting that this very ambiguity “implies that help and kindness and loyalty are owed where they are perhaps by no means merited,” and that within families we are liberated from the narrow practice of judging the validity of “others’ claims on us” against the claims we have historically made on the others now doing the claiming.

Steve Pemberton’s story of family ambiguities begins here.