Genealogists beware.

A software company is marketing a new program to Internet advertisers that could quickly generate Web sites full of extensive, but fake, family trees.

Critics say the approach appears to be part of a new money-making scheme to lure people who search for family names on Google, Yahoo or other search engines to Web sites that use bogus data to help ensure they appear high on "hit lists." They then make money if visitors click on advertisers' links.

They worry that novices might download false information that is designed to look real, and then corrupt others' family trees if they share that bad data online or through family history databases such as those offered by The Church of Jesus Christ of Latter-day Saints or the commercial Utah-based Ancestry.com

However, Don Harrold, co-creator of a program called "Fake Family," which he sells for $75, says data it produces has "absolutely zero chance" of matching any real person or family. He says he has offered the program to fewer than 30 self-described Internet advertisers, so its use is not widespread, and he has not made money on it.

Why make it then? "Why not? I enjoy trying to find ways to create computer simulations of organic life," Harrold told the Deseret Morning News.

But online chat groups of both genealogists and Internet advertisers are buzzing about what the new program could do to genealogical research, and why Harrold is marketing it, even if, as he says, to a small group.

Dan Eastman, author of Eastman's Online Genealogy Newsletter, wrote this past week that he believes Harrold "wants to flood the Internet with bogus genealogy material, all for the purpose of making easy money."

Online information that Harrold wrote says his product can "create thousands of pages of unique . . . content with almost no effort. Neither humans nor search engines will be able to tell whether the content is 'real' or 'generated.' "

How could that make money?

Josh Anderson, an Internet advertiser from Idaho, who also is a genealogist concerned about the product, explains Web hosts can program their sites to display "sponsored links." Advertisers pay search engines to have these appear on screen whenever certain key words such as "genealogy" are part of a search.

When such links are clicked by a visitor, the Web site host and search engine company split revenue from an advertiser. (Of course, Web sites can also offer other forms of advertising.)