SALT LAKE CITY — Jim Brewster submitted his DNA through the company Family Tree DNA and discovered some relatives through DNA matches that he had never met or heard of, he shared in RootsTech’s “Understanding DNA Testing for Geneology” class Feb. 4.

Upon investigation, Brewster learned that he and a newfound distant cousin were descended from Irish sisters. With this new knowledge, they were able to communicate online to help one another fill in gaps that were previously roadblocks to their genealogy research. DNA testing led them to each other, which in turn opened up a new database of family information.

Brewster also delivered a biology crash course, reminding the diverse group that we each have 23 pairs of chromosomes that dictate the genes for our entire bodies. These chromosomes include sex chromosomes, the X and Y, which can be vital in tracing human migrations all the way back t­o the time of Adam.

The DNA tests aren't just for finding current relatives, he said. With the sample, DNA is compared to control samples for regions of the world.

"This can be particularly useful for those that are adopted or donor-conceived," he said, since they typically do not know the specifics of their heritage.

For example, the technology can reveal how much of a person's DNA is influenced by Scandinavian, Middle Eastern or Western European genes. Full siblings could have genes that match entirely different heritages, yet still close enough to recognize them as full siblings, he said.

Three DNA tests are available: autosomal, a general test that scans all the typical chromosomes; Y-DNA, which is only available for men, and mtDNA, which traces the mitochondrial DNA that each person inherits from his or her mother.

"You may be wondering, 'What's the best test?'" Brewster said. "But it's really a question of "What's the best tool?' Think about your end goal."

These tests all have different benefits that can correlate with whatever information a person is seeking. For finding relatives, stick with the autosomal test, he said. When looking for information on a male member of your famiy history line, the Y-DNA test could be particularly useful, just as the mtDNA test for seeking a female.