When schoolchildren turn to the chapter on Christopher Columbus’s humble origins as the son of a weaver in Genoa, they are not generally told that he might instead have been born out of wedlock to a Portuguese prince. Or that he might have been a Jew whose parents converted to escape the Spanish Inquisition. Or a rebel in the medieval kingdom of Catalonia.

Yet with little evidence to support them, multiple theories of Columbus’s early years have long found devoted proponents among those who would claim alternative bragging rights to the explorer. And now, five centuries after he opened the door to the New World, Columbus’s revisionist biographers have found a new hope for vindication.

In 2004, a Spanish geneticist, Dr. Jose A. Lorente, extracted genetic material from a cache of Columbus’s bones in Seville to settle a dispute about where he was buried. Ever since, he has been beset by amateur historians, government officials and self-styled Columbus relatives of multiple nationalities clamoring for a genetic retelling of the standard textbook tale.

Even adherents of the Italian orthodoxy concede that little is known about the provenance of the Great Navigator, who seems to have purposely obscured his past. But contenders for his legacy have no compunction about prospecting for his secrets in the cells he took to his grave. And the arrival on Oct. 8 of another anniversary of Columbus’s first landfall in the Bahamas has only sharpened their appetite for a genetic verdict, preferably in their own favor.

A Genoese Cristoforo Colombo almost certainly did exist. Archives record his birth and early life. But there is little to tie that man to the one who crossed the Atlantic in 1492. Snippets from Columbus’s life point all around the southern European coast. He kept books in Catalan and his handwriting has, according to some, a Catalonian flair. He married a Portuguese noblewoman. He wrote in Castilian. He decorated his letters with a Hebrew cartouche.

Since it seems now that the best bet for deducing Columbus’s true hometown is to look for a genetic match in places where he might have lived, hundreds of Spaniards, Italians, and even a few Frenchmen have happily swabbed their cheeks to supply cells for comparison.

“You would be proud to know that the man that goes to America the first time was Catalan,” said Jordi Colom, 51, an executive at a local television station whose saliva sample will help test the contention that Columbus was born in Catalonia, the once-independent eastern region of modern Spain that still fosters its own language, culture and designs on independence.

No chance, said Renato Colombo, 62, a retired Italian engineer who proffered his DNA to reassert his nation’s hold on the status quo. “It has never been in doubt that he was from Liguria,” the region in northwest Italy of which Genoa is the capital, he insisted. “In his personality, there are the characteristics of the Genoese, mostly represented by his project and his visceral attachment to money and his determination.”

Mr. Colom and Mr. Colombo are both “Columbus” in their native tongues. And along with their names, each inherited from his father a Y chromosome — a sliver of DNA passed exclusively from father to son — which would have been virtually unchanged since the 15th century. A Columbus match to either man’s Y chromosome would tie him to that paternal line’s Italian or Catalonian home.

“What I want to write is the final book on Columbus, and I will not be able to do it without science to settle this,” said Francesc Albardaner, who was seduced by the possibility that DNA — a tool whose answers are treated as indisputable fact in courtrooms and on TV shows — would endorse his deeply held belief in the Catalonian Columbus.

Mr. Albardaner, a Barcelona architect, took more than three months off work, called 2,000 Coloms and persuaded 225 of them to scrape their cheeks at his Center for Columbus Studies in Barcelona. The swabs along with 100 Colombos collected in Italy are being analyzed by Dr. Lorente at the University of Granada and scientists in Rome.

A Colom match could overturn conventional wisdom about the nationality, class, religion, and motives of the man who began the age of American colonization. On the other hand, an association with Colombo DNA would cement Italy’s national pride in a man who remains a hero to many, complaints from American Indians he slaughtered, Africans he enslaved and Vikings who got there first notwithstanding.

But some petitioners think it is a waste of time to scour the phone book for Columbus’s long-lost kin. Insisting that they know who Columbus’s father really was, they are asking Dr. Lorente to perform a 500-year postdated paternity test. The government council president of Majorca, for instance, has paid him to examine the exhumed remains of Prince Carlos of Viana, the one-time heir to the Catalonian crown who reportedly fathered a son with a woman on the island whose last name was Colom.

The vials of royal DNA in Dr. Lorente’s freezer also include contributions from two living members of the now deposed Portuguese royal line: those of the Duke of Bragança and the Count of Ribeira Grande who argue that Columbus was a member of their family — the product of an extramarital affair involving a Portuguese prince.

“This is the true story, forget the Italians, forget the Spanish,” said Count Jose Ribeira, 47, a real estate developer in Lisbon who attended the dedication of a new Columbus monument last year in the Portuguese town of Cuba that claims to be Columbus’s birthplace. If it is, all three samples should contain the same Portuguese genetic imprint.

But this year, anyway, the Columbus Day parade in New York will feature Maserati sports cars, flag throwers from Siena and Lidia Bastianich, the Italian cooking show host, as grand marshal.

Those who had hoped DNA would crash the Italian party expected a genetic pronouncement from the scientists on the 500th anniversary of Columbus’s death last May. Or last Columbus Day. Surely by this one. After all those centuries in a crypt, however, a mere trace of DNA was all that could be extracted from Columbus’s bones, and Dr. Lorente has said he is loath to use it indiscriminately.

To make things even tougher, he has found that Catalonian Coloms and Genoese Colombos are so closely related it is hard to distinguish them with the standard Y-chromosome tests. So he is searching for more subtle differences that would allow him to link Columbus to a single lineage.

“My heart,” Mr. Albardaner said, “will not endure so many delays.”

Others have accused Dr. Lorente of nationalist bias, of covering up results that suggest Columbus was a Jew and of withholding a historical treasure from the Western world.

“Will Lorente continue to hide what the scientists know concerning Columbus’s DNA?” asked Peter Dickson, a retired C.I.A. analyst whose self-published book on Columbus argues that he was part French, part Italian, part Spanish and part Jewish, in an e-mail message to fellow Columbus buffs. “Will he remain silent on Columbus Day once again?”

Dr. Lorente says he will. And in the absence of data, rumors are flying.

Olga Rickards, a Lorente collaborator at Tor Vergata University in Rome, has been quoted as saying that she “wouldn’t bet on Columbus being Spanish.” A graduate student of Dr. Lorente’s who had studied the Colombo DNA led Italian newspapers to believe Columbus was from Lombardy, north of Genoa, although she had apparently never seen Columbus’s DNA. And Nito Verdera, a journalist from the Balearic island of Ibiza, who says the explorer was a Catalan-speaking Ibizan crypto-Jew, cited leaks from Dr. Lorente’s team that link Columbus to North Africa.

“I’m very sorry about the great expectation among some historians that they all want the DNA to confirm their hypothesis,” Dr. Lorente said. “But science needs its time and has its pace.”

If Columbus was an adopted name, as some scholars believe, tests of Coloms and Colombos will have been in vain. Moreover, with dozens of generations separating all those Coloms, Colombos, princes and counts from Columbus’s time, a long-hidden adulterous liaison could have severed the Y-chromosome-and-surname link.

Even with a match questions will remain. What if Coloms moved to Genoa or Colombos to Barcelona? Today’s distinct regional identities may not be reflected in the genetic code of the earlier era.

Mr. Albardaner still brings Columbus novices to the Historic Archive of Protocols in Barcelona, where they can hold a yellowed note from the 15th century filled with the calligraphic scrawl of the man he believes stumbled upon the Caribbean while looking for a western route to India.

He is less sure now that there will be a precise answer to who Columbus was or where he was from, but he is still hoping it will come from the DNA.

“Maybe it will say he’s from Catalonia. Maybe it will be a complete lockout. Maybe we find his DNA is completely dissimilar to any known DNA, he comes from Mars, well, perfect, O.K.”

“Then,” he said, “I stop.”