When they run into those inevitable brick walls in search of their ancestors, more and more genealogists are turning not to census data, military logs or death notices.
They're spitting into vials.
Genetic testing can enable researchers to identify living people with whom they share common kin and figure out where in the world distant ancestral homes were and long forgotten ethnic roots.
Such testing services are widely available and steadily improving, but there are limits to what they can accomplish. To maximize its potential, Utah-based GeneTree (www.genetree.com) now provides counseling to help genealogical searchers determine what they can learn through genetic tests, which tests to take and who in your family can provide useful samples.
"If you get a little creative and test your mother's brother, you can extend Y chromosome into different areas in your pedigree," said Scott Woodward, chief scientific officer at the Sorenson Molecular Genealogy Foundation, which operates GeneTree. "We can help identify collateral people in your pedigree."
Bennett Greenspan, founder and president of Houston-based Family Tree DNA (www.familytreedna.com), estimates 90 percent of genealogical searchers have tapped their genes, or those of a surrogate.
"The problem with genealogy, especially before the Internet, is you always run into a roadblock," Greenspan said. "This could be my surrogate piece of paper."
Greenspan, whose company was among the first in 2000 to offer genetic tests for genealogy, used genetic testing on his own pedigree to determine whether his cousin descended from someone he found in an online database who lived in a Ukrainian village and had the same surname.
The two men's Y chromosomal DNA matched up, proving what Greenspan couldn't using traditional genealogical tools such as birth and marriage certificates, census data, immigration documents and military records.
These paper resources are indispensable, but they don't always survive and are not much help for unraveling adoptions and "illegitimate" births. While records might be destroyed in a fire or a flood, DNA abides and never lies.
You don't need a doctorate in genetics to use this science in your genealogical searches, but a basic understanding of DNA is crucial for those who want to put it to use.
You inherent half your DNA from each parent, packaged mostly in 23 pairs of chromosomes. One of these pairs determines your gender, XY for male and XX for female. The Y chromosome passes from father to son, generation after generation, while mitochondrial DNA, or mtDNA, passes unchanged down the mother's line. Men have mtDNA, but they do not pass it along, while women lack a Y chromosome.
The two main tests used in genetic genealogy analyze the Y chromosome, peering down your paternal lineage, and mtDNA, revealing clues about your maternal line. They typically cost $179. Both are like searchlight beams that illuminate a focused area while leaving much in the dark. For example, five generations deep you have 32 great-great-great grandparents. Either test can connect you or a surrogate with just one.
"People need to know that going in. It's a very selective view," Woodward said. "They are powerful tools for what they are designed to do, but you have to be careful about expanding their scope."
Important differences exist between Y chromosomal DNA and mtDNA. For starters, women don't carry a Y chromosome, so they have to choose a male relative if they want to use this test. And the Y chromosome is much longer than mitochondria, 58 million base pairs versus 16,569, according to Greenspan.
"There's a lot more meat that we can harvest when we are looking at the Y," Greenspan said. "I always suggest that if someone is trying to prove something with mtDNA, then we need to test the entire molecule."
Family Tree DNA maintains a database of 330,000 individuals it has tested. If it discovers people in the database with whom you share an ancestor, it will provide email addresses and the country of origin.
Increasingly, genetic testing is examining autosomal DNA, areas of the genome that are neither mitochondrial or Y chromosome. But these tests are more costly, in excess of $300. Because these tests cast a much wider net, the information they yield is harder to interpret.
(Contact Brian Maffly of The Salt Lake Tribune at firstname.lastname@example.org.)