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.