Y-DNA (Y chromosome DNA)
How Does Y-DNA Help With My Genealogical Research?
Using Y-DNA to further your genealogical efforts is a three step process:
- Obtain your Y-DNA profile
- Find an Y-DNA match in our database
- Collaborate with the matching individual to make a genealogical connection
The Y chromosome follows the paternal line. In western cultures, this is the same path as the surname. Once you have obtained a Y-DNA profile, you can use that information to query our database. Any man with a matching genetic profile is considered your paternal relative. By contacting and connecting with these DNA matches, you can investigate, verify, or discover more information about your paternal line.
What Is Y-DNA (Y chromosome DNA)?
A chromosome is the structure in which DNA is packaged. Individuals normally have 23 pairs of chromosomes (for a total of 46). 22 pairs are called the autosomal chromosomes, and the 23rd pair is the sex chromosomes (two X chromosomes for females and one X chromosome and one Y chromosome for males).
Y-chromosome DNA (Y-DNA) has a strict paternal inheritance, meaning that it is passed from father to son, and is useful in researching your paternal line.
How is Y-DNA Tested and Reported?
The Y-chromosome contains 59 million bits of information, each of which is encoded by a "base pair." Looking at all of these base pairs is impractical, so geneticists have identified a number of specific chromosome locations that can be used for analysis and comparison.
Your Y chromosome results are presented with two sets of information: the markers (loci) you had tested, and your values (alleles) at those markers.
Most Y chromosome markers are named with the prefix DYS, which stands for DNA Y chromosome Segment, followed by a number, which is used to identify the specific marker on the Y chromosome.
Your values, or alleles, when taken together, make up your DNA profile. It is this set of numbers that identify your direct paternal line. These numbers refer to the number of times a short segment of DNA is repeated on your Y chromosome.
For instance, a particular genetic sequence at marker location DYS391 might be:
The number of times “TCTA” is repeated is the "value" that is reported on a Y-DNA test report. In this example, a lab report would show DYS391=10 for this marker.
While every man has these repeat regions, the difference between men is how many times the segment repeats. One man may have a 10, representing 10 repeated segments, while another has 11.
How many markers should I have tested?
In some ways, considering how many DNA markers to have tested can be thought of like a telephone number. Consider the same seven-digit telephone number that has different area codes. The seven-digit number looks the same, but by dialing them with the area code, you would be calling two very different locations. The same thing is true about DNA testing. When only a few markers have been tested, adding more values can drastically change your understanding of the results.
If we compare a limited number of DNA markers (for example, 12), then it's possible for two individuals to have the same marker values, yet not be closely related. Testing for more markers helps avoid this possible ambiguity. In general, the more markers tested, the easier it is to distinguish individuals and family tree branches. For this reason, we recommend the 46 marker test and believe a 33 marker test is the lowest amount of markers you should have tested.
For questions on which test to use please speak with one of our DNA consultants.
