By Joanne Ostrow
Denver Post Staff Columnist

It’s not uncommon for black American families to have assumed for generations that they are of African lineage with the possible exception of a long-ago Cherokee ancestor. High cheekbones, straight hair, lighter skin – these are among the markers typically cited to make the argument that a great-great-great-grandparent must have been an American Indian. According to those who know, this is a favorite parlor game of African-Americans debating their ancestry.

Turns out not everyone is descended from African kings and Indian chiefs. Once science gets involved, even the proudest African-Americans may turn out to be awash in European blood.

An eye-opening PBS series reveals that long-honored family histories are subject to radical rewrites when genetic research is introduced to the genealogical detective work.

Tears, intrigue and insights flow out of “African American Lives,” a four-hour miniseries to be broadcast on two Wednesdays, this week and next (8-10 p.m. both nights on KRMA-Channel 6).

Beyond its dramatic scientific research, the program offers a collective history of African-Americans, reaching back generations to slavery and earlier.

Hauling the family tree into the laboratory, Harvard’s TV-friendly intellectual, Henry Louis Gates Jr., introduces DNA analysis to the record, along with genealogy, oral history and family lore. He’s digging into his own past to demonstrate the process. He’s taking apart assumptions along with DNA samples. And he’s taking celebrities with him.

Break it to Oprah gently: She’s not really Zulu.

Tell Quincy Jones to brace for a shock.

And imagine the unnerving realization for Gates – the noted black studies scholar is 50 percent white.

Gates, the W.E.B. Du Bois professor of humanities and chair of the African and African American Studies Department at Harvard University (he’s better known as “Skip”), acknowledges that using celebrities is a blatant lure to get young viewers interested.

And why not? It requires the same diligence to track Oprah’s roots through the dusty record books as it does anyone else’s. This way, viewers get a look at the research methods and historical twists with the additional spark of a superstar’s emotional response in close-up.

Along with probing the limbs of his own family tree, Gates pieces together histories for Whoopi Goldberg, Winfrey, Quincy Jones, former NASA astronaut

Mae Jemison, actor Chris Tucker, T.D. Jakes, pastor of a megachurch in Texas, and several others.

Gates follows paper trails, property-tax records, the Mormon genealogy collection (the Family History Library), and uses the Internet (a site called ancestors.com) to trace the individual family trees through as many branches as possible.

When the paper trail runs out, he turns to science. With a few swabs from the inside of the mouth, it’s sometimes possible to pinpoint the tribe in Africa where the subject is originally from.

In one case, the DNA testing makes it possible to learn that a prominent African-Americans’ great-great-grandparent was – surprise! – Asian.

The research is tricky, he notes, since African-Americans weren’t treated as human beings with first and last names until the 1870s U.S. Census.

A goal of the series – apart from the giving PBS something to air during Black History Month – is to encourage young inner-city kids to pursue their own genealogies. An outreach program accompanying the broadcast is set up to teach people to use the Internet for such research.

Aspiring ancestor hunters should know, however, that the admixture test, which reveals what percentage of one’s DNA is African, European, American Indian or Asian, isn’t cheap. It’s available on the Internet but costs roughly $300.

Gates doesn’t think much of designating a Black History Month, the coldest, shortest month at that. For him every day is a celebration of and inquiry into black history.

He tells his students “there are 35 million African-Americans; there are 35 million ways to be black.” This revealing and emotional series documents a few of them.