When it was discovered that the male “Y” chromosome was passed from father to son, relatively unchanged, for generation upon generation, Y-DNA testing became a wonderful new ‘tool’ for use in conjunction with traditional genealogical research, since surnames also follow the father-to-son pathway. Results can be compared between two, or more, men to discover whether they have a common ancestor within a genealogically relevant time frame, meaning from the time period when surnames were adopted – roughly 600-700 years ago.
You can make use of Y-DNA testing with several different goals in mind. One goal would be to provide additional proof for existing research. As an example, I have worked, with several others, for many years to research a large group of BERRYs who can first be documented in Augusta County, Virginia in 1745. Y-DNA testing reveals that all of these men were closely related genetically, so we can say that Y-DNA supports and confirms our research.
Perhaps a more common usage of Y-DNA testing is when we do NOT have a good paper trail very far back in time. Y-DNA testing could identify a particular branch of your surname as a close genetic match, which would allow you to compare research with your matches, potentially being able to discover even earlier generations.
An equally positive outcome occurs when Y-DNA testing reveals that a lineage we had ‘thought’, or perhaps ‘hoped’, was connected to ours is shown by Y-DNA results to not be ‘genetically’ related. Initially, it may be a great disappointment to discover that the surname you are researching was not related to a group with the same surname, however, this outcome does allow you to move on and stop knocking your head against the proverbial brick wall that never was going to break open.
Sometimes, participants do not find a match at first. This is usually because not enough people within that surname have elected to participate in Y-DNA testing. The results are of record within the DNA project and, quite often, new testers eventually come along who do match.
Some people, new to Y-DNA testing, think that it is a magic bullet, which will identify a specific ancestor by name. However, the Y-DNA results only provide a probability estimate of the time frame that a common ancestor most likely lived. You will still have to discover the traditional kinds of documentation to identify the common ancestor, but you now have a focus.
I would strongly urge anyone contemplating Y-DNA testing to test as many markers as possible. For example, at FamilyTreeDNA (FTDNA), I would start at the 37 marker level, and go to the 67 marker level if feasible, but the 37 marker test is the gold standard and the minimum I would recommend. The more markers you test, the more you are able to maximize and refine the probability estimates for the time frame that the common ancestor lived. I would also strongly urge anyone contemplating Y-DNA testing to try to find an existing surname project and use the same company that those participants used so that you could compare all of the same markers – which also maximizes the probability estimates. To this last point, do not ignore variant spellings of the surname as a group to join.