James LeVoy Sorenson loved his 1999 trip to Norway retracing the steps of distant ancestors. When he got home, he invited geneticist Scott Woodward to his office and told him, "Let's analyze all of Norway's DNA!"

The scientist gulped. Both men recall that Woodward stared across a conference table and declared, "That would cost $500 million. I don't think you can afford it."

Sorenson shot back, "Oh, yes I can."

The 83-year-old Salt Lake resident and entrepreneur is a billionaire several times over thanks to his development of plastic catheters and heart-monitoring equipment plus a half-century of wise investments. Sorenson ended up dropping the Norway idea, but he did so to pursue an even greater ambition. He wants to dominate the fast-growing field of connecting people with their roots through genetic testing.

Sorenson scientists are popping up everywhere from California to Cameroon to build a database of human DNA. So far, they have persuaded 50,000 people from nearly 100 ethnic groups to hand over DNA samples and family lineages.

The data belong to the nonprofit Sorenson Molecular Genealogy Foundation. But the man who made a killing on Utah real estate and Abbott Laboratories stock also sees a glint of profit potential in his latest obsession. A Sorenson company called Relative Genetics Inc. is selling tests for $50 and up that help people figure out where they fit in the database — and sometimes connect with specific ancestors who lived hundreds of years ago.

New technology is setting off a genealogy gold rush inconceivable in an earlier era when people had to rely on old courthouse records and half-remembered family lore. Scientists now have several ways of using DNA to determine ancestry. The simplest involves the Y chromosome, which is found only in men and accumulates small changes over the centuries. If men have nearly identical Y chromosomes, it means they share a recent ancestor going up the male line. Another method uses mitochondrial DNA, which passes from a mother to her children. It can be used to determine ancestry through the female line.

Such tests used to cost thousands of dollars apiece. Now they're relatively cheap — and some entrepreneurs see both scientific and commercial potential. This month, the National Geographic Society announced it was teaming up with International Business Machines Corp. and Family Tree DNA of Houston to build a database of 100,000 samples from ethnic groups around the world. National Geographic is selling a service — for $99.95 plus shipping and handling — in which people can send in their own DNA and find out where they fit on humanity's family tree. For example, it might show that a person's ancestors on the male line came out of Africa, through Central Asia and into a particular part of Europe.

Family Tree DNA and several other U.S. companies already offer more narrowly focused services designed to help amateur genealogists solve family riddles. African Ancestry Inc. of Washington, D.C., uses DNA to help individual black Americans figure out what part of Africa their ancestors came from. Trace Genetics Inc. of Richmond, Calif., provides a similar service for Native Americans, among others.

To this race, Sorenson brings nearly 60 years of experience as one of America's most prolific entrepreneurs. The son of a Mormon livestock-yard operator, he was born in 1921 and grew up in a tar-paper shack in Yuba City, Calif. He hoped to become a doctor, but instead spent part of World War II as a missionary for The Church of Jesus Christ of Latter-day Saints in Maine. After 11 years at Upjohn pitching drugs to doctors, he formed a series of health-care companies. Some of his designs for surgical masks and plastic catheters still are used in hospitals today. In 1980, Sorenson sold his medical-device company to Abbott Laboratories for $100 million of Abbott stock. He kept the shares and profited greatly as they soared.

As a Mormon, Sorenson belongs to a faith that places great emphasis on family history, sometimes with the goal of posthumously baptizing ancestors. For most of his career, though, genealogy seemed too humdrum to command his attention. His wife, Beverley, took the lead, filling their home with pictures of their 47 grandchildren and various forebears. In an interview, she proudly noted that she is a descendant of John Taylor, leader of the Mormon church in the 1880s.

Eventually, Sorenson's views changed. "The older you get, the more you feel connected with those who came before," he says. "You even start to hear your dad's voice when you speak."

In the 1990s, Sorenson helped relatives develop charts of his forebears as far back as 15th-century Switzerland. He got his feet wet in the genetics business by acquiring a DNA-testing service called GeneTree in 1997, focusing on paternity issues. And he befriended Woodward of Brigham Young University, who was analyzing sheepskin DNA in ancient parchments. "I told him, 'Scott, why don't you study people instead?' " Sorenson recently recalled.

Woodward soon embraced the idea of building a database that could rival anything in academia. After Sorenson got back from his trip to Norway in 1999, the two settled on a plan for the Sorenson foundation. It would collect small samples of many populations, focusing on the Y chromosome. Once typical profiles for each one were established, people could plug in their own data and figure out what region their forebears along the male line might have come from.

The idea didn't stop there. Woodward decided to get detailed genealogies from those who contributed their DNA. Eventually, he figured, some people would be able to submit their DNA sample and find a connection not just to a region but also to a specific ancestor. To protect donors' privacy, the Sorenson team decided not to release details about anyone born in the past 100 years.

In early 2000, notices began appearing on BYU's main campus in Provo, inviting students to visit Woodward's office so they could contribute blood samples and at least four generations of family history, including birthdates and country of origin. Unsure whether anyone would bother, Woodward offered participants $10 apiece for their trouble.

Right away, Woodward's office was mobbed. Seventy students hovered outside the door at 9 a.m. on the first sampling day, March 6, 2000. It took eight hours to process them all. That stampede repeated itself daily for months.

While BYU students' enthusiasm helped generate thousands of samples in the first few months, it also left the project overweighted with people of Anglo-Saxon, Germanic or Scandinavian origin. Seeking greater diversity, one of Woodward's graduate students, Ugo Perego, pored through Census Bureau data in search of unusual immigrant enclaves in the United States.

Starting in 2001, Perego visited towns such as Red Lodge, Mont., to sample people of Finnish origin; Malad City, Idaho, for Welsh-Americans; and New Bedford, Mass., for Portuguese-Americans. To get past airport security with his attache cases full of test tubes, Perego recalls that he had to get a letter from the Centers for Disease Control.

When a Mexican politician visiting Utah offhandedly suggested studying the indigenous Totonac population, Sorenson researchers rushed days later to a remote corner of eastern Mexico. No matter that researchers hadn't heard of the Totonac until then. They returned with more than 100 DNA samples.

Most of the Sorenson effort overseas targets countries of ancestral significance to many Americans, such as Nigeria and China. Sorenson scientists also decided in 2003 to emulate other geneticists' adoption of a painless alternative to blood sampling. A brisk mouthwash rinse, it turned out, could collect enough cheek cells to generate reliable lab results.

In 2003, the project severed its ties with BYU and relocated to Sorenson's corporate headquarters in Salt Lake City. The university was running out of lab space, and the switch helped allay any concerns among non-Mormons that the project might have a religious agenda.

Leaving BYU also gave Sorenson free rein to develop the business side of his genealogy project. In 2001 he had started Relative Genetics as a for-profit company to handle the samples coming in from the Sorenson foundation. Within months, it started selling testing services to the public, looking for business among those curious about their ancestors.

The more data that the Sorenson researchers gather, the more they crave. "We started out believing that 100,000 samples would give us a good cross-section of the world," says Woodward. Now the foundation's latest forecasts call for 500,000 within five years. It is also beginning to expand into mitochondrial DNA, the kind that traces the female line.

Customers who get their Y chromosome tested at Relative Genetics can log on to the Sorenson foundation's Web site and find out for no additional charge what other families have similar genetic markers. Disclosures are most extensive for likely matches with people born at least 100 years ago. For example, the database might show that a man is closely related to a man of the same surname born in England in 1860. Because of a rule barring release of detailed information for people born in the past 100 years, Web-site visitors can't get names and phone numbers of living people who might be distant cousins. Eventually, the foundation may set up ways for limited contacts to occur if all parties want them.

Other research centers are growing fast, too. Family Tree DNA has gathered 31,000 samples so far, and it groups this data into 8,000 surname files so that amateur genealogists can figure out how they relate to people with the same or similar surnames. "If someone's last name is Mauch, they can look at Mock, Mok, Mauck and plenty of other variants in our database," says Bennett Greenspan, chief executive of the Houston company. Sorenson site users are guided only toward the best genetic matches, without the same freedom to probe many surnames.

The new National Geographic-IBM venture has a more academic focus. It is led by Spencer Wells, a leading advocate of the theory that all modern humans descend from a small group that lived in Africa about 60,000 years ago. Wells hopes his data will fill in large blanks in the history of human migrations since then. People who send DNA samples to National Geographic won't be able to connect with specific relatives; they'll only get a general sense of the path their ancestors took in the last 60,000 years. (Separately from its regular business line, Family Tree will conduct the DNA tests on National Geographic's behalf.)

Bonnie Schermer, a novelist in Mishiwaka, Ind., suspected for years that her grandfather kept separate families in North Carolina and the Midwest. Last year, she met Sorenson researchers at a genealogy gathering and they offered to test free of charge genetic samples of Schermer's father and a North Carolina man she thought might be a descendant of her grandfather. Their DNA markers were essentially identical.

Schermer says the news was a shock at first. But now, she says, it gives her a deeper understanding of her past and "more sympathy for our ancestors and their frailties." It also has led her to make friends with her long-lost North Carolina cousins.

In other cases, Sorenson data has disproved theories about family ties. Woodward dealt last year with a Pennsylvania family. The family had grieved for decades about a male relative who wandered away from his parents during a New York City visit as a toddler in 1910, and was never seen again. They speculated he had ended up in an orphanage. If so, the Pennsylvanians thought that a casual acquaintance — the son of a New York orphan — might be their cousin.

The orphan's son closely resembled the Pennsylvanians in appearance. When DNA tests were run, however, it became clear the two families weren't connected. "They were disappointed," Woodward recalled, "but at least they had an answer."

The testing has helped Sorenson make a discovery of his own: One of his distant ancestors probably was a Russian Jewish bookkeeper named Jakob Levinsohn. "I guess I'm a member of the tribe of Levi," he says.