AMERICA: For many Americans, a visit to Ellis Island to find records of their relatives' immigration is an essential part of growing up and an important moment of discovery about who they are, writes Denis Staunton
Irish-Americans can often trace their ancestors to a particular parish or townland with a precision that puts many native Irish to shame and other ethnic groups trace their family histories just as fervently.
However, African-Americans have no Ellis Island, and Henry Louis Gates jnr, a literary critic and head of Harvard's African and African-American Studies department, says he has long envied the ease with which his white friends can trace their roots.
Most black Americans, whose ancestors were brought from Africa as slaves, can trace their family histories backwards for only three or four generations.
Until the abolition of slavery, public records listed slaves only by sex and age, sometimes with a first name and usually as part of an inventory that included buildings, livestock, corn and other property.
After years of frustration, Gates decided to do something about it and he invited eight other prominent African-Americans to join him in using modern genealogical techniques and genetic research to find out more about their forebears.
The result is a four-part television documentary called African American Lives which started on PBS this week and which the New York Times has described as "the most exciting and stirring documentary on any subject to appear on television in a long time".
Gates's fellow subjects, who include media mogul Oprah Winfrey, musician Quincy Jones and actors Whoopi Goldberg and Chris Tucker, don't live ordinary lives today.
But their family stories share many elements that are common to millions of black Americans, not least in the mystery that surrounds their ancestry.
The programme starts with its subjects' own early years and works back through the 20th century, into the 19th and beyond, culminating in the results of DNA testing that show where their ancestors came from originally.
Raped at nine and pregnant at 14, Oprah Winfrey's life changed when her father, a barber with a firm set of values and a determination to save his daughter from the streets, imposed strict discipline and pushed her into taking education seriously.
What Winfrey didn't know was that her father was following a family tradition stretching back more than a century from when an ancestor who owned land after the Civil War set up a school for black children.
Gates turns up remarkable stories about hitherto anonymous people who made heroic advances in the 19th century, emerging from slavery with next to nothing and overcoming apparently insurmountable odds to buy land and gain an education.
Chris Tucker's great-great-grandfather sold off pockets of land at below market prices to black neighbours so they would not join the great migration north and thereby saved the black community in Flat Rock, Georgia.
One of the documentary's recurring themes is Gates's search for information about his own great-great-grandmother, Jane Gates, who was born into slavery but managed to buy a house in Cumberland, Maryland after the Civil War. Family tradition held that an Irish-American slave owner called Samuel Brady had given her the house after he fathered her children, but DNA testing showed that Gates and Brady were not related.
Gates expected the DNA results showing information about his subjects' origins in Africa to be the documentary's most dramatic moment. Gates himself got the biggest surprise when he discovered that 50 per cent of his DNA is European, and his roots lie as deeply among Ashkenazi Jews as in Africa.
But his guests were more stirred by the light shed on their American heritage and the stories of forbears they could more easily imagine and identify with.
As Bishop TD Jakes, a popular religious leader, put it when he learned about the struggles of his own family through the 19th century and into the 20th: "It's not just a gathering of data, but a gathering of hearts and tears and souls that makes us sing like we do and clap like we do and dance like we do and live like we do. It's because we suffered like we did."