Last year, a Guyanese woman who runs a natural-hair salon asked me to be one of her models for a magazine ad. Like me, she is militantly opposed to blacks straightening their hair (approximately 75 percent of black women do). I was thrilled. In the working-class black community I come from, an invitation like that is an honor; women pore over these hairstyle magazines like treasure maps.

When I saw the photos, however, the thrill was gone. I'd been airbrushed at least four shades lighter, and my dark eyes had magically gone gray. My nappy hair looked fabulous, though.

Those photos have become powerful totems for me. In part, they remind me of how desperately some of us long to be less black. They are also compelling, however, because of their power as another kind of metaphor. Like most American blacks, I have many whites in my family tree, about whom I know nothing and whom I have never known how to incorporate into my identity. When Howard University unveils its African DNA database this summer, we who were swindled out of every link to the past except skin color will be able to find out more about our heritage. Whether we want to know because we merely want to fill in the blanks or because we secretly long to be more white, the question will be the same: When we uncover the mixing and mingling in that past, what then will we make of our selves?

To create the Howard database, scientists have assembled 2,000 samples from 40 populations across West Central Africa--present-day Ghana, Nigeria, Sierra Leone and Angola--where the bulk of the American slaves came from. African Americans who want to find their true roots can take tests that examine both mitochondrial DNA, which passes unaltered from mother to child, and the Y chromosome, which passes through the male line. The database also has samples of European, American Indian, Asian and Hispanic DNA for cross-referencing of non-African genes--evidence of the the endemic rape of enslaved black women and subsequent mixing of the races. Apparently, some 30 percent of the black males tested so far have shown European lineage through their fathers.

Judging from their Web site, the creators of the Howard database expect African Americans to spend $ 300 each in search of their specific African origins: The tests, the site says, afford "us the opportunity to find out more about ourselves by examining our genetic makeup and developing a genetic fingerprint. We encourage you to join us in our endeavor as we work towards designing a method to help individuals determine their African ancestry." No suggestions are offered about what to think of our Indian, Asian or European heritage.

A glaring omission, given that there are few black families who don't brag about the whites and Indians (all chiefs) in their lineage and lie about how hard it was to make their hair stand up "like that" during the reign of the Afro. But that intellectual void cannot last long; many blacks will be obsessed with their newly discovered inner honkies, though not all will admit it. Self-hating blacks fetishize the non-blacks in their lines in a desperate attempt to be more than, or better than, black. The well-adjusted are merely curious and weary of being understood one-dimensionally; they simply long to understand more fully who they are.

In either case, it's long past time blacks opted out of blackness. No one would think twice about a latter-day Alex Haley learning the language of his ancestral tribe, donning its traditional garb, lobbying for it politically, even converting to its religion or immigrating to its modern homeland. But there will be many with unaccounted-for Irish, German or Norwegian genes in the woodpile. Is a Negro allowed to leave the geneticist's office a retroactive Scandinavian? An all-of-a-sudden-Arawak? A dreadlocked Dutchman? Probably not.

This conundrum centers around the "one-drop" rule: One drop of African blood, no matter how dimly recorded in your genetic code, and you're black. Blackness is the ultimate subtraction, the ultimate lessening, the ultimate tainting of its opposite--whiteness. What is the definition of white? That's easy: no blacks, nonwhite Hispanics, or Asians ever, paddling in your gene pool. That classification exists nowhere in nature: There are more genetic differences between members of so-called racial groups than between racial groups--but everywhere there are benefits and burdens to be distributed.

Ironically, it's often minorities who cling most fiercely to this imprisoning notion. Many blacks criticized golf phenomenon Tiger Woods for not identifying himself as one of us and instead adopting "Cablinasian." As one comedian said, "Let him get caught speeding with a white girl in the car . . . . He'll find out real quick he's [black]." Woods's Thai mother--her culture, her genetic contribution, her love and nurturing--was blacked out.

Now who's minimizing whose culture? One needn't accept that it's bad to be black to strain at the narrow seams of it; one need only accept that the designation is woefully inadequate and often downright meaningless. A Nigerian who immigrates to America in 2000 has virtually nothing in common with the descendants of American slaves, but we're both conceptually freeze-dried down to that one aspect of our selves.

For all the wars it's caused, lives it's wrecked, art it's fueled, "identity" is a pretty arbitrary concept, as much so as "race." Think of transracially adopted children. Think of racially indistinct children whose parentage is never established. Once you know what's in your hardware, then what? You stop eating pork? You start wearing kilts? Hating whitey?

In her 1979 novel "Kindred," black science fiction writer Octavia Butler shows her heroine, Dana, repeatedly dragged back in time to be with her foremother, a slave named Alice. The brutal, repugnant young master Rufus has forced her to be his mistress, albeit a pampered one. The other slaves hate her; she hates herself for her occasional softenings toward him. To her horror, Dana eventually realizes the disgusting Rufus is the ancestor who has the hold on her and who calls her to him through the mists of time to do a daughter's duty. Not the noble, dignified slave. The Massa. Dana's really there to safeguard the man who makes her foremother's life a living hell. If Rufus dies (he's accident-prone: he almost drowns, is shot, loses the will to live when Alice escapes), she will never be born. Nor will she be born if Alice kills herself or successfully runs away before Hagar, the progenitor of Dana's family line, is conceived. In rape.

Is Alice more important to Dana than Rufus? Should she embrace Alice's heritage and despise Rufus's? Most would say yes. But stop for a moment. Without Rufus, there would be no Dana. Without slavery, there would be no Jesse Jackson. No Leontyne Price. No Anatole Broyard. No Tiger Woods. No Willie Horton. No jazz or gospel. No rap. No tap. No underclass. No me.