AN OVERVIEW of Y-DNA

How does Y-DNA work?

Y-DNA works very differently from autosomal DNA that most people test. Y is one of the two sex chromosomes,
handed down from father to son only, so information from this test is solely about the ancestry of a direct
patrilineal line.

Whilst a female does not inherit Y-DNA, she can still explore this line by asking a suitable relative to test, such
as a brother, male cousin or uncle connected through her father’s line.

Unlike autosomal DNA, where segments of DNA can come from any ancestor, Y-DNA can come from one line only, so it can help to confirm that line, or in some instances deny it. Either way, this can be vital information.

Take a Y-DNA test

The only company that offers a database of matches for Y-DNA testers is familytreeDNA.com (FTDNA). You will want to test here so that you can compare your DNA with that of others who have tested.

The results you will see will vary depending on what level of Y-DNA that you test, but everyone will get a list
of available matches and also see the ancestral story of your haplogroup, presented in a simple and
informative way through FTDNA’s Discover tool.

The number of matches in your list varies between testers and is, of course, dependent on who else has tested. Your match list is updated whenever new matches test.

Haplogroups

Y-DNA is handed down intact for many generations at a time. However, mutations did (and do) occur and it is
these that allow Y-DNA testing to define which haplogroup a person belongs to.

Mankind can trace its ancestors back to a single group of people living in Africa. From there, members of this group migrated to different areas and unique mutations were developed within each of these separate groups; this created offshoots of the original haplogroup. This continued for many thousands of years.

Each new mutation
is given a sub-number and, simply put, that is what your haplogroup classification is.

Y-DNA matches

There are various levels at which you can test your Y-DNA and the results you get will reflect which of these
levels you tested. For example, a Y-37 test will examine 37 markers (or STRs) on the Y chromosome and the Y-111 test will compare a further 74 markers.

The most complete test is the Big Y-700, which looks at a
minimum of 700 markers.

Each marker is matched against those of everyone else to generate your matches for each level to which both of you have tested.

The more markers that are tested, the more refined the matching will be.

Genetic distance and time prediction

Looking at your list of matches, a genetic distance of 0 with a match means that the marker you both share is
exactly the same, with no known mutations on that marker.

A genetic distance of 1 means there is one known
mutation on that marker and so on. The more mutations there are on a marker, the further back the most
recent common ancestor is likely to have lived. However, at the lower levels of testing, the most recent common ancestor to a match with a genetic distance of
0 could still be many generations back.

FTDNA has a tme prediction calculator to give you probabilities of
how far back the common ancestor lived. You can find this by clicking on the TiP icon at the right of the match
details.

A matching surname increases the chances of a match being in more recent times, but there can be many social and cultural reasons for a match not having the same surname.

The use of surnames as we know them today has exosted for a relatively short timeframe - as late as the 1900s in some cultures. Others took surnames of a clan or tribe, so do not actually have paternal connections. There could be an illegitimate birth or someone could have adopted a different surname because of personal circumstances, or just because they wanted to.

Big Y

The Big Y test examines many more markers as well as SNPs, which are mutations or new branches on the Y-DNA haplotree. The results from this test will show your unique mutations and provide a block tree which illustrates how your matches fit into this tree through those unique mutations.

Unlike Y-37 and 111, the Big Y test is not static and your block tree is continually updated as more people test
and matching mutations are identified.

Because Big Y tests are more extensive and include SNPs, your haplogroup will be the most recent available,
meaning that any matches are more likely to be more recent too. This also means that you may find a match
that was not apparent at a lower level of testing.

Genealogists are turning increasingly to Y-DNA to find out more about their ancestral journey through time and their patrilineal connections more recently.

There has never been a better time to discover what a Y-DNA test can reveal for you!