In the past week there has been an interesting convergence of inquiries into the nature of truth. James Frey’s A Million Little Pieces triggered deep epistemological soul-searching about whether simple lies can constitute “emotional truth.” After a swirl of media confusion, a sound tongue-lashing from Oprah Winfrey seemed to seal up the answer as a resounding Not On My Dime.

At the same time that Frey’s soap opera was playing itself out, researchers in France were searching for any charred relics at the site where Joan of Arc was said to have been burned at the stake. They want to subject any putative remains to DNA testing. Why one would want to do this has become something of an issue in the European media: She didn’t have children, the site of her martyrdom is in dispute, the legitimacy of any so-called relic would be highly contested. But the pursuit of knowledge in so attenuated a context has raised questions about the hunger for certainty in the face of such uncertainty. What are the limits of historical insight? How many graves shall we dig up to settle old scores? What are the possibilities of knowing absolutely?

Here at home, the American press has been busy dissecting Henry Louis Gates’s exploration of his roots and those of a handful of other prominent African-American figures, including comedians Chris Tucker and Whoopi Goldberg, scholar Sarah Lawrence-Lightfoot and, of course, Oprah Winfrey. It is a fascinating series of TV programs, particularly from the perspective of the discipline of history. It reveals the peculiar difficulties of tracking lines of descent through slavery, the sales of human beings that acknowledged no family ties, the absence of last names, the absence of first names in some cases and the necessity of consulting not just census records but also “the master’s” property holdings for listings of possible relatives. The reconstruction of family history is like an archeological dig, part intergenerational storytelling, part study of migratory patterns, part recovery of commercial transactions and part science.

The science du jour is, of course, DNA testing, and Professor Gates could not be more incautious about its salutary promise for African-Americans in search of a sense of self. Here is where the programs run into some rather careless uses of that science. On the one hand, DNA testing can be quite useful in establishing certain kinds of family relation. Gates’s own test results showed that he has an Ashkenazi foremother, and that he has no relation to Samuel Brady, the white patriarch he’d grown up “knowing” as the man who impregnated his great-great-grandmother. His family lore had never hinted at what the Wall Street Journal dubbed his “Yiddishe Mama.” By the same token, nothing had prepared him for Brady’s not being his direct ancestor. Indeed, one of Gates’s cousins remains adamant that the test must be wrong. If the test is right, he insists, there are two truths. One is the story he grew up with, the other is what the DNA says.

Somewhere in between what the DNA says and what shaped the family account is a gap that is something like a lie. A secret passing from black to white? An act of assimilation or aspiration? A myth to hide some shame, some rape? A change of identity to escape to freedom? Yet I do hesitate to think of it as precisely on the same moral level as the kind of “lie” that James Frey is said to have told in his book. There is something very human about the repetition of family stories until they become epic rather than literal, the burying of family secrets, the lying of ancestors, the reinventions of migrants, the accommodations of raw ambition, the insulations from terrible shame. This is, I suppose, distantly related to James Frey’s addled manipulations; it might also be related to, but of a different order than, the magical thinking of mental patients or character-disordered people or victims of great trauma. There is something so commonplace about the kinds of family mysteries that Gates’s inquiries reveal–particularly in the American context. It is part of how many, many of our ancestors, regardless of where they came from, reinvented themselves in the New World. NYU law school Professor Jessie Allen describes the “magic” of legal remediation as follows: “What ought to have been prevails over the past.” Family stories ritualize the past in a very similar way. It is part of what Professor Robert Pollack, head of Columbia University’s Center for the Study of Science and Religion, calls the “eschatology of repair.”

If there is value to this kind of “emotional truth”–if I can be permitted that term–it is important not to confuse it with the sort of truth that DNA tells us. So while DNA can undoubtedly pinpoint certain aspects of our ancestry, it does not make literal sense to say, as Gates does to Oprah Winfrey: “You’ve got education in your genes.” Of course, he was speaking metaphorically at that moment, using the human genome as a metaphor for a pattern of socialization, a family habit, a thirst for knowledge modeled by parents. But at other points in the program that metaphoric dimension is applied rather more carelessly–and more dangerously. “I’m 50 percent white,” says Gates. But there is no more an allele for “whiteness” than there is for “education.” “White” is a malleable social designation with a freighted history. Were his Ashkenazi ancestors to appear before us today, they might be called white, but as Eastern or Southern Europeans coming to America a hundred years ago, they probably would not have been considered so.

It behooves us to be less romantic about what all this DNA swabbing reveals. I worry about the craving to “go back to Africa,” to “connect with our Yiddishness” or to feel like new doors have been opened if we have an Asian ancestor. The craving, the connection, the newness of those doors is in our heads, not in our mitochondria. Rather, it is the process of superimposing the identities with which we were raised upon the culturally embedded, socially constructed imaginings about “the Other” we could be. The fabulous nature of what is imagined can be liberating, invigorating–but it is fable. If we read that story into the eternity of our blood lines, if we biologize our history, we will forever be less than we could be.