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From the discovery that presidential hopeful Barack Obama is descended from white slave traders to the realisation that the majority of black Americans have European ancestors, a boom in "recreational genetics" is forcing America to redefine its roots.
Al Sharpton walked into a South Carolina pine forest just outside the sleepy southern town of Edgefield and stopped at a cluster of tooth-like unmarked gravestones.
This was the former plantation on which a few generations ago his ancestors had worked, lived, loved and died, owned as property by white masters.
"You must assume that it's family here," Sharpton said, referring to the abandoned slave graveyard.
A few weeks previously Reverend Sharpton, one of America's most outspoken black civil rights leaders, had not known of the cemetery's existence.
But researchers had explored his genealogy and broken the news to him.
Sharpton's story had an astonishing twist: the genealogists discovered his ancestors had once been owned by the ancestors of Strom Thurmond, the Senator and former segregationist who once ran for president on a racist platform.
The phrase "ironic coincidence" did not begin to cover it.
Dozens of reporters tagged along when Sharpton first visited the Edgefield woods, yet it was clear he was genuinely stunned by what he called "the greatest shock" of his life.
"It profoundly affected him," said Tony Burroughs, a genealogist who worked on the project.
Sharpton was not alone. America has embarked on an amazing journey to explore its own past.
Millions of Americans of every creed and colour are exploring their family histories in a genealogy boom that is redefining who they are and what it means to be American.
The internet has allowed people to find obscure information that was previously locked away on dusty library shelves. They are also using modern DNA techniques to research their racial history.
Blacks are discovering they have white blood, whites are finding black relatives. Native Americans are growing in numbers, not because of a high birth rate, but because many Americans are discovering unknown native ancestors written in their DNA.
And it is impacting right up to the highest in the land.
Just after the Sharpton story broke, other genealogists revealed they had discovered presidential hopeful Barack Obama's family - through his white mother - had also once owned slaves.
That means the man who hopes to become America's first black president could be the direct descendant not of black slaves, but of white slave-owners.
Literally, nothing is now as black and white as it once seemed.
Last year, Professor Peter Fine at Florida Atlantic University asked a class to take a DNA test.
His bet was that most of the class - of whom the majority saw themselves as whites of European descent - had no real idea who they were.
He was right. Of 13 students, only one turned out to be completely European. The rest displayed a mixture of European, Native American, African and Asian genes. The one black student turned out to be 21 per cent white.
Fine himself - who admits to looking like a corn-fed stereotype of a white Midwesterner - discovered he was a quarter Native American.
"I honestly think these tests could have a large effect on American consciousness of who we are.
"If Americans recognise themselves as a mixed group of people, that could really change things,' he said.
As millions of Americans take DNA tests, they are discovering America's strict racial lines are, in fact, blurred.
One-third of white Americans, according to some tests, will possess between 2 and 20 per cent African genes.
The majority of black Americans have some European ancestors.
For a few hundred dollars, Americans can radically alter the way they think of themselves through a new industry that has been dubbed "recreational genetics".
Dozens of companies now offer DNA tests, ranging from the basic - breaking down a person's racial profile into broad categories such as European or Native American - to more detailed ones which claim to identify specific regions or tribes of the world. It has led to some bizarre developments.
One American discovered Jewish genes in his DNA and is now seeking to get Israeli citizenship.
Some white college applicants, upon discovering they have African or Asian or Native American DNA, have applied for scholarships aimed at minorities. Some researchers will go to extremes to get samples from others. People have stalked newly discovered relatives, even going through rubbish to snatch DNA samples if they refuse to volunteer them. Some have even plucked hair from newly deceased relatives.
For the celebrity-minded, DNA profiles of descendants of famous historical figures have been released on the internet, including Thomas Jefferson, General Robert E. Lee, Marie Antoinette and Genghis Khan.
One website plans to add others soon, including DNA profiles of people related to Columbus and Billy the Kid.
DNA research is having a transforming effect on millions of lives. That is what happened with Issac Carter, 33, one of Fine's students.
He is black but his family history told of a Native American ancestor, while his tests showed he was a lot whiter than he thought and had no Native American blood at all.
In fact, the whole world of Native Americans has been thrown into turmoil. Many tribes, some of whom have become rich on the back of casino gambling, are now flooded with calls from people suddenly claiming to have discovered their Native American background.
A country known for its racial faultlines has discovered a new sense of fluidity. The identities emerging are complex and multi-faceted.
But the one group for whom DNA tests have really stoked a sense of turmoil is black Americans. In America's long history of immigration, they are the people who have no "old country" to look back to.
Scientists are scouring America and Africa collecting DNA and trying to find common genetic markers that allow links to be made between black Americans and African tribes. One of the most prominent is the Roots Project, run by Boston scientist Dr Bruce Jackson.
He has collected DNA samples from 10,000 black Americans and is comparing them to DNA excavated from slave burial grounds in America and back to specific African tribes.
Yet experts say the science is far from perfect.
They point out that beyond a few generations any human is descended from a huge pool of ancestors. The fact that a great-great-great-great-grandparent was from Ghana does not make one Ghanaian.
The science is also largely reliant upon statistical analysis and not always exact DNA markers.
Professor Troy Duster of New York University, says: "There is a cultural feeling that DNA evidence is sacrosanct. But a kind of false precision is rampant right now."
But such a debate only highlights how complex race has become in America. It is not just a matter of skin colour; it is also about how society perceives you.
Professor Fine may be a quarter Native American, but he admits his pale complexion means he will always be seen as white: "I know I still have all the privileges of being white in America."
GREATER knowledge can pose troubling questions. While hosting African American Lives, Professor Gates, one of America's most eminent black scholars, was stunned to find he was half European. He had more ancestors in France and Ireland than in Africa. Such discoveries unsettle even the greatest mind.
In the show, Gates lamented what this meant to a proud black American. "I have the blues," he said, and then asked: "Can I still have the blues?"
Barack Obama is seen as black by most Americans. Yet that skin colour comes from his Kenyan father, who met his white mother, from Kansas, at college.
That prompted some leading black commentators to claim that Obama is not a real black American (or not black enough). This, in turn, led a group of genealogists to trace Obama's mother's family back to before the Civil War - and they found that some were slave-owners.
That is how - if he wins the 2008 race - America's first ever black president will be the direct descendant of white slave-owners.
Most blacks joining the genealogy boom expect to find a slave ancestor. But when it happens the experience can be upsetting.
They must face the reality of descending from chattel slaves, living in bondage, and being beaten and brutalised at the hands of white masters. "These were our ancestors. That is kind of rough to take," said genealogist Tony Burroughs.
Lisa Salley is a successful engineer whose work has taken her all over the world. She has found slave ancestors, and mulattos, too - usually the result of rape by white masters.
She has found evidence of her family being split up on the whims of their white owners. It has left Salley with a sense that she does not really belong in the land of her birth. "I have no intention of retiring in the US."
For many black Americans, the moment of discovering a slave ancestor has a sweetness to it. A vindication, too. "I call it a genealogy high," said Allen McClain. "It makes it all worth it."
There are happier moments that show how rigid ideas of race and identity are beginning to melt in America. Even Salley had one of those moments.
In researching her family she discovered a slave ancestor who had children with her white master, Thomas Kinsey.
She then traced the Kinseys to their modern descendants and got in touch. She met an elderly white woman, Myrtle Linder.
Though she was white and Salley was black, the two women were likely distant cousins. Linder was feisty, still chopping wood in her own backyard despite her advanced years.
Salley recognised the same independent spirit she felt in herself. "I thought: 'Now these are my people, too,' " she laughed. And they were.
The two women became firm friends. After all, they were family. Skin colour did not matter.
It is individual moments like this that can slowly change a nation.
- Observer
