Genetic genealogy complements traditional family history research by confirming — or disproving — ancestral relationships. The most popular test, Y-DNA, examines genetic “markers” on a man’s Y chromosome. Because the Y chromosome changes little (if at all) as it’s passed from father to son, men know they’re related if their Y-DNA matches.
Here’s an example: James Zavacky and Peter Zavatsky want to find out whether they’re related, so each takes a 25-marker Y-DNA test. In comparing their results, they discover that 24 of those 25 markers are identical, with a mutation at marker 449:
That 24/25 match indicates that the men do indeed share an ancestor.
But what about the mismatching marker? Each value here shows how many times a genetic pattern repeats itself on that particular marker. James Zavacky and Peter Zavatsky don’t have the same number of “repeats” on marker 449 — but their values are close. That mutation in the Y chromosome signals that the men aren’t as closely related as men who match perfectly.
Not everyone is satisfied with the results. Many take this test to prove American Indian ancestry, but the desired evidence may not appear — partly because family lore is wrong and partly because this test is shallower than others (that is, it reflects fairly recent genera-tions). Also, it can be difficult to distinguish between American Indian and East Asian heritage, since these groups have distant ancestors in common. See <www.dnaprintlog.org
> for an interesting collection of test-takers’ expectations versus their actual results.
From the February 2005 Family Tree Magazine