America now knows that Rob Lowe has an un-American ancestor. Recently, on the NBC program "Who Do You Think You Are?" the actor, who played the freedom-loving idealist Sam Seaborn on "The West Wing," learned that his great-great-great-great-great-grandfather, a Hessian soldier, bore arms against the Continental Army and was taken prisoner at the Battle of Trenton during the winter of 1776.

"You mean to tell me my five times great-grandfather was trying to stick it to George Washington?" the actor said in astonishment.

Lowe's televised odyssey from California to Washington, D.C., to Trenton to Germany might have entailed more time and money than most researchers can spare. But embarking on a quest to trace one's familial roots is not extraordinary; it's a popular pastime. In fact, the genealogy research site Ancestry ( gained 800,000 subscribers -- an 80 percent rise -- since November 2009, said J.P. Canton, the site's public relations manager.

With the availability of digitized online records, reconstructing one's family tree is easier than ever, say professional genealogists -- but some see pitfalls amid the ease of access.

For a yearly membership of $155.40, Ancestry alone provides 9 billion historical records, including census, immigration, birth, marriage, death and military records, said Anastasia Harman, the site's lead family historian. The site recently added a digitized version of the 1940 census.

There is no shortage of enthusiasts.

"People are more willing to do it because they can do it in their pajamas at midnight," said Jan Alpert, past president of the National Genealogical Society, an organization with 10,000 members that focuses on promoting genealogical education through courses, publications and conferences.

Kathleen W. Hinckley, a certified genealogist with the Association of Professional Genealogists, agreed. Before records became digitized, she said she operated by "cranking microfilm and writing letters to courthouses." Now, she spends 80 percent of her research time on the Internet, using sites such as Ancestry and FamilySearch ( to find clues.

Those clues abound.

FamilySearch, a free online service provided by the Church of Jesus Christ of Latter-day Saints, adds 40 million new records from 130 countries to its site and has millions of users each month, said Paul Nauta, the site's manager of public affairs.

Other sites dedicated to helping researchers track ancestors as well as the digitization of many newspapers have put information at the public's fingertips, too. Still, problems arise.

"People getting into it are so used to convenience that they have the perception that if it isn't online, it doesn't exist," said Nauta, who points out that only about 20 percent of genealogical records are online.

Many times, Hinckley's clients give up just because digitized records haven't been indexed, she said, adding that she likes Ancestry for the convenience it affords her, but also because it boosts her business. When people underestimate the amount of time and research involved even with these e-luxuries, they come to her.

"The two strengths of Ancestry is that they have a great database and they have a great search engine," Alpert said. "But at some point, you get stuck."

The farther back one traces a family's roots, the less helpful digitized records become, she said. While sites store records that date to the 17th century -- and some beyond -- the quality of the data varies based upon where one's ancestors lived and their socioeconomic status. African-Americans whose ancestors were enslaved before 1870, for example, won't find any information for them by going through digitized vital records, Harman said.

To hurdle these obstacles, Alpert recommends using vacations to visit the Library of Congress or state libraries, or local libraries, courthouses and churches that store county vital records as yet undigitized.

That's what Lowe did, and it's advice that Jerry Coghlan is heeding, as well.

When his mother died in 1996, Coghlan, a retiree living in Hilton Head, S.C., found a cemetery deed in her house that led him to a lot in a Philadelphia church graveyard. Buried on that lot, with no markers, were 15 of his ancestors, including an older brother who died in infancy and his great-grandfather, the Coghlan family patriarch, Patrick Coghlan. Through records from the Catholic Church and Ancestry, he was able to learn more about his ancestors. He even located the house they'd inhabited on Hanover Street in Philadelphia.

Because Patrick Coghlan emigrated from Ireland, Jerry needs to travel to Ireland to research the family line further.

"The big questions became, 'What county in Ireland?' 'When did they come?' and 'How did they get here?'" Coghlan said.

Trying to answer even those questions through Internet records proved difficult, because the spelling of the family changed over the years, he said. But after meeting Alpert, the possibilities narrowed. Through Irish Records Extraction Database, Alpert was able to provide Coghlan with a short list of counties for him to investigate, which he will do next year on a family trip.

In addition to spelling issues, Alpert warned of another common problem: Not every tree on Ancestry is accurate.

"If you can't find two or three records that really tie a family together, then you really have to question your records," she said.

Of course, genealogy also has a price -- "$500 will get you started," Alpert said -- but for the savvy researcher, the chances of success are good.

"Everybody has a germ of an interest to see where it all started," Coghlan said.