When Stuart Nixon began searching for his family roots, the Watergate crisis was in full bloom and he decided to examine the Nixon file in the Library of Congress.

The Alexandria resident was undaunted when a worker told him the file was "off limits." Fifteen years later, after conducting dozens of interviews and searching the depths of seemingly countless libraries, he has traced his ancestry as far as the early 19th century, and, "as far as I know," he said, "I'm not related to that other Nixon."

Nixon's interest in genealogy grew so dramatically since that time that in 1981 he founded the Hearthstone Bookshop, one of a few genealogical bookstores nationwide. Nixon and his wife Tammy, who has traced her Pennsylvania Dutch ancestors to 1725, are in the process of moving the store from Alexandria's historic district to more modern, spacious quarters on Rte. 1 outside the Capital Beltway.

"At least it's a Colonial-style shopping center," Tammy Nixon said.

The six-year-old bookshop, a popular attraction for tourists, is crammed with how-to books, local histories and genealogical flow charts. Accessories include photographic restoration equipment, family tree T-shirts and fliers advertising genealogical conventions.

"Everybody has a family tree," reads a sign in the window. "Let us help you climb yours."

Nixon began looking into his past largely because of his father. "My father always put his family first, and he has a great interest in history," Nixon said. "But he never knew much about his family. There wasn't much information."

Nixon discovered early in his quest that genealogical resources were difficult to find. Often turning to mail-order companies for information, he says, he felt robbed of valuable time that could have been spent researching.

"I said there has got to be a better way," he said last week. "There ought to be a store you can go to to get what you need."

Hearthstone was born soon afterward.

Nixon eventually left his job as a senior editor at a national magazine to devote his energies to the bookstore.

"There's great similarities between genealogy and journalism," he said. "You have to be a detective. You have to be accurate . . . careful . . . persistent."

Nixon says his customers range from experienced genealogists to curious novices. On a recent day, customers popped in to the store to share their latest successes -- such as finding a long-lost relative or discovering a fascinating family fact.

"We think of ourselves more as a service organization than a bookstore," Nixon said. "We hear wonderful stories."

Though a number of Nixon's customers are familiar with the tricks of the genealogical trade, he says some people confuse it with genetics, geriatrics and gemology. "You wouldn't believe some of the calls we get," said Tammy Nixon.

Even those who know the basics have some learning to do, Stuart Nixon says. "Genealogy is not just collecting names and dates on a piece of paper and storing them away," he said. "That is not genealogy. That's just the bare bones. What you're trying to do is make these people come alive, reach back and touch these people."

And that is why the bookstore has volumes covering ancient customs and fashions. After uncovering ancestors' names, the genealogist searches for clues about their family life, church affiliations, occupations and even physical characteristics.

Any scrap of detail is treasured by a genealogist, Nixon says.

His eyes light up when he tells the story of a relative who received a medical degree in six months during the Civil War, or about his great-great-grandmother who rode for miles to attend church.

With all its informational resources, Washington is the best place in the nation to pursue one's past, Nixon says.

The problem with Washington, he said, is that its fast-paced inhabitants are generally unwilling to spend the years it often takes to track down a particularly elusive family member. "They want quick results," he said.

Nixon cautions that a genealogical search cannot be completed in a weekend. "Genealogy doesn't work that way," he said. "It's like a good meal. You have to sit down and do it right, really enjoy it and just take your time."

But Nixon says these technological times also have helped genealogy. The latest sensation at the bookstore is genealogical software for home computers, which speeds the search by eliminating cumbersome paper work.

"It has tremendous potential," he said.