If present trends continue, tracing a family tree in the 21st century will be a veritable nightmare. No longer does a founding patriarch's name flow intact from one generation to the next.

Although the trend is more of a trickle than a tidal wave--and predominant among young professionals--there is now an array of married-name options, each variation with its staunch supporters.

Besides the traditional taking of the man's name, women are keeping their maiden names, using both last names or their given names professionally and their married names personally. The newest wrinkle: Men taking their wives' names in one form or another.

The reasons for breaking with tradition are as varied as the names.

"Taking the man's name is one of those societal things men never would have tolerated, and for some reason women have," says labor union executive secretary Sherry Showalter. "I just knew I didn't want to do it."

And she didn't when she and Renny O'Connor were married in 1978.

"I tried to talk her into taking my name at first," admits O'Connor, a math teacher at St. Albans School for Boys. "But then she asked, if the custom were the other way around, would I like to change my name? What could I say? I couldn't ask her to do something I wouldn't like doing myself."

O'Connor, 40, feels more strongly, however, about passing his name on to any offspring. Showalter, 30, has agreed, saying it wouldn't bother her in the least to have a last name different from her children's.

When Anne Ballew and Tom Porter were married three years ago, they took each other's last names as their middle names: She is now Anne Porter Ballew and he Tom Ballew Porter. Porter, 25, an attorney with the Justice Department, came up with the idea.

"The traditional way of her taking my name wasn't balanced," he says. "I like having that bond with Anne and her family."

By not simply becoming "Mrs. Thomas Porter," says Ballew, 27, a copy editor for the American Society for Microbiology, she has "not been metamorphosized beyond recognition by marriage."

Children's names? "We'll cross that bridge," says Ballew, "when we get to it."

Karen Leggett, reporter for WMAL radio, and Tharwat Abouraya, vice president and general manager of Bianco Travels in Silver Spring, decided when they were married last year to keep their established names professionally. But their personal credit cards, checking accounts and other identification bear the hyphenated Leggett-Abouraya.

Their children will bear her surname as a middle name, and his for their last. "It's fine if I want to run around with that long a name," says Leggett, 33, "but I wouldn't want to stick a child with it."

"A lot of my friends wish they had the courage to do it," says Tharwat Leggett-Abouraya, 32. "Most of them never thought of it."

Andy and Pat Jenkins-Murphy of Fairfax never considered anything other than a hypenated name when they married five years ago.

"It just seemed appropriate--right," says Andy, 42, a writer, who considers their choice more a personal than social statement. "You maintain a part of that original identity as well as the new one of starting up a new family."

"It stands for sharing, a true union," says Pat, 30, a trainer/nurse at George Washington University Hospital. "That's why it's so important to me that Andy did it, too. You're both equal partners in a marriage . . . with equally strong backgrounds and equally strong futures."

Another advantage: People always remember them, although the "It's-a-hyphenated-name" explanation has become a regular part of the introduction.

And more than one credit-card company has refused to hyphenate their two names, running them together instead as one long, unpronounceable blur.

VISA even sends out a form letter stating that the company is unable to process hyphenated names. Spokesman Wayne Rasmussen says the company's computers have not been programmed to handle hyphenations. Asked if they will be, he would only say that VISA was "looking at ways of supporting our customers' name changes ."

Deciding whether Jenkins or Murphy went first, the couple says, had nothing to do with being "his" or "hers," but was based on the sound of the two names together. Pat's went first "because it naturally flowed that way."

The former Andy Murphy acknowledges that a few eyebrows were raised when he changed his last name to Jenkins-Murphy, but the only place he had any trouble was at the Virginia motor vehicle department. At first they told him he needed a court-ordered name change. When he tried again a year later, he found a more receptive clerk.

Otherwise, he merely filled out forms and presented his marriage certificate when necessary to adjust Social Security and other forms of indentification.

In contrast, my husband (the former Hugh Taft), who teaches history and ethics at St. Albans School, was told in no uncertain terms by the Washington Social Security office that he had to go through a legal name change in order to add a hyphen and my last name to his.

The process would involve several court appearances, a court fee of $50, publishing the name change three times in a major newspaper at a total cost of $40, sending $10 copies of the court order to all creditors and allowing time for people to file objections to the change before it became legal.

"It seems an ironic justice," muttered Taft-Morales, "that it's a male-chauvinist world, and I am the one who has to pay for it."

When asked to clear up the matter, Social Security spokesman Phil Gambino (after apologizing for the misinformation), set the record straight:

"Along with some form of identification, a marriage certificate is more than just cause for a name change--for a man or a woman. And that's national policy."

Meanwhile, Taft-Morales, 26, says he often feels like a witness at a feminist rally. "Most females cheer and pat me on the back. Males either just say, 'That's interesting', or ask, 'Why?' "

Not men like Michael Gottlieb, 27, an attorney with the Washington firm of McKenna, Connor & Cuneo, who has taken the name of his wife, Liz Berney, 26, a doctoral student in organizational psychology at the University of Maryland.

The couple spent several months discussing their decision before their marriage last spring. Hyphenating their names, they decided, merely placed the burden of choice on the next generation.

Among other options suggested by Michael Berney: the adoption of an entirely new last name, perhaps an old family name that had died out or a combination of parts of their names such as Bernlieb or Gottney.

"Michael's somewhat political," cracks Liz. "At one point he suggested taking Gandhi."

When none of their alternatives seemed suitable, Berney decided it was time to put into practice his views on feminism.

"Things should not be decided on the basis of traditions of a male society," he says, "but after negotiations between partners."

Liz Berney's only regret is that they were not sensitive enough to a generational difference in attitudes toward names. While the Berneys viewed the traditional custom as "a sexist institution . . . It never occurred to us that his family might be hurt."

"I really love my parents," says Michael Berney. "I also like the separate identity I have with Liz as a family unit."

After a District Court of Maryland clerk told him he would need a legal name change to become Michael Berney, he researched the law himself and found that for a woman to take her husband's name, she "must represent herself consistently afterwards as having that new name." The law doesn't specify that men need do anything different.

So the former Michael Gottlieb sent letters to his creditors, law schools and other concerns stating that he was married, "and from this day forth would be known as Michael Berney."

And then there's the case of Katharine Lustman-Findling, 63, whose hyphenated name combines the surnames of two husbands. "My maiden name," she says with a chuckle, "got lost in the shuffle."

Emotional attachment to a 30-year marriage (she was widowed in 1971), children and grandchildren bearing the name "Lustman" and a professional career established under that name led her to retain her first husband's name when she remarried seven years ago.

"It's a symptom of the times," says Lustman-Findling, a research associate and teacher of child development at Yale University in New Haven, Conn.

It never occurred to her, she says, as a bride in 1941 not to take her husband's name. But if she were marrying for the first time today, she says she would hyphenate her maiden and married names. "I finally understand what it means to young women to have to drop their name."

"I hope we reach a time when the decision of what name to take is no longer made automatically by society," says Karen Leggett-Abouraya. "When all the options are acceptable, and credit cards have room for everybody's name."