Photos like this one, of children named John and Sadie, are waiting for genealogists like you to find them.

A virus is a small, infectious agent that replicates inside the living cells of organisms. I know there are millions of types of viruses, and I am no virologist—but I am sure that I have one that has been around since biblical times.

You might recall what some refer to as "the begats" in the Bible. This is an example of the genealogy virus. Once it breaks out in your system, you are infected for life and you might be infectious to others. Some younger family members may pretend to be immune and feign disinterest, but as they get to be seniors, they are likely to exhibit signs of being infected, as well. Actually, I think all people carry it in their systems, although it may be dormant in a few.

The infection got me the day I connected to the Internet in 1999 and entered my great-grandfather's name at Google. When I saw a page from a book about the history of Cherokee County, Kan., recounting a speech my great-grandfather gave there at the Old Soldiers' Reunion in 1906, I was hooked.

I may have first been infected with the virus at age 14, when my mother and I visited Boston and I saw a street named for one of our ancestors. I think the virus had been incubating since then and was aggravated in 1973 by a cousin who updated and compiled an extensive family tree. My cousin, who was blind, devoted years to calling relatives all over the world. His wife wrote letters and put an amazing amount of work into this tree without the use of a computer or the Internet.

Since the advent of the Internet, no longer is genealogy relegated to your retired cousin or your Great Aunt Ella, who had the leisure and funds to correspond with relatives or visit the far-flung places where family information might be held. With the Internet and its hundreds of genealogy sites, mailing lists, and family trees, genealogy has become a worldwide virus—disguised as a hobby—that millions have contracted. And although it can go into remission, it is incurable.

Although the rich can hire professionals, like some do on the TV show "Who Do You Think You Are?," they miss the fun of following clues and finding results that we ordinary mortals enjoy.

One of the best side-effects of genealogy is connecting with distant kin and kind friends with the same disease—people you meet in the Internet's genealogical spaces. Connecting with fourth cousins twice removed who are looking for the same ancestors, and who share your enthusiasm, is a joy. Some wonderful people with whom I've interacted have gone to the trouble of visiting their local cemeteries to photograph tombstones and post the names on a free site called findagrave.com. One lovely day I found my great-great-great-grandparents' tombstones in Kentucky there, posted by a stranger who was just being kind.

Some finds can really surprise you. I have a best girlfriend of almost 70 years' duration. We haven't found any ancestors in common, but we have shared our successes with one another. I know her ancestry well. While browsing online in the Library of Virginia, I entered the name of an ancestor of mine. It's a peculiar name, which is genealogically desirable. The name "Fauntleroy" was proudly passed down through the generations until it was stuck on my poor grandfather, who never wanted anyone to know it.

I typed in the name of my four-greats-grandfather, Fauntleroy Dye, and three records popped up. They pertained to his being a Tory sympathizer during the Revolution. I already knew that he had been jailed for this, but these records were new to me. They were letters urging the governor of Virginia to have him jailed. Then I looked at the signature. My best friend's ancestor, Richard Henry Lee, wrote them. I could hardly wait to call her!

As I research my family tree, I wish I had paid more attention during history classes in school. You just cannot go very far back without wanting to put your family's lives into historical perspective.

With a little help and the use of our own or one of the library's computers, we can each be the Sherlock Holmes of our family. The Johnson County Central Resource Library on 87th Street has a great genealogy department. With a library card and a password, you can access from home a free search program called Heritage Quest, where many records and books are waiting for you. The Johnson County Kansas Genealogical Society meets at that library on the fourth Saturday of each month, and visitors are always welcome.

With guidance and self-control, you can keep your genealogy virus within bounds and enjoy its duration. Most experts agree that the best treatment for a virus is drinking lots of water, staying home, and taking pain meds. My genealogy virus treatment is to shut off the computer and talk to a human being—in my case, my husband, who does not care whether my seventh great-grandpa, Wolfgang Kaefer, born in 1670 in Ansbach, Mittelfranken, Germany, was a goose herdsman!