The Y-chromosomal DNA test is a valuable test for serious genealogists and for confirming relatives both in a genealogical time frame and beyond. The test, also called yDNA is offered by FamilyTreeDNA.com (FTDNA). and can provide researchers where their direct paternal ancestors came from, their locations in historic times and how they migrated throughout the world.

 

It examines the DNA from the male-specific Y chromosome from the XY chromosome pair found in the nucleus of every cell of males. This DNA is passed down with virtually no mutations each generation from fathers to their sons only (the patrilineal line). This test is only for men although women interested in their father's paternal line can have a brother, father or other male in her fathers patrilineal line take the test. Since the Y-chromosome is passed down with the surname in most western cultures it can be one of the most useful tests. It can also help confirm and determine what family line an autosomal. FTDNA provides you with a list of those closely matching you from those who have tested with their company with an estimate of the relationship.

 

Just like each of the 23 pairs of chromosomes the Y chromosome recombines (one chromosome from the mother and the other from the father break and trade segments with one another) with the X-chromosome for each son. However the y chromosome only recombines at the very ends of the Y chromosome leaving the vast majority unchanged. When copying errors (mutations) have occurred in a prior male ancestors they are therefore passed down unchanged from father to son.

 

A yDNA test conducts an examination of many specific sites along the chromosome (SNPs) which together provide a general profile of a patrilineal line's haplogroup. Men who belong to the same haplogroup are on the same major branch of the ancient human family tree. This allows yDNA testing to provide a family's paternal deep ancestry for thousands of years. The yDNA haplogroup can also be estimated by testing as few as 12 STRs. If at some later point SNPs are also examined, the haplogroup can be confirmed and even further refined to subclades (smaller branches on the ancient family tree).

 

Who can take this test?

Only men can take the yDNA test. Women can determine their father's patrilineal line by having a brother, father or any surviving descendant of one their father's  patrilineal ancestor. For example, to test the relationship of two third cousins of mine, a brother and sister), only the brother could take the test. Their father's, father's, father's father (patrilineal great great grandfather) was the same as mine.

 

What are its strengths?

It strengths are the ability to study with a focus on your patrilineal line and also delve in further into your deep ancestry (many hundreds or thousands of years into the past). Of key importance is an ability to determine the haplogroup, an overall profile of determinative locations on the Y chromosome which will match men with others that share a patrilineal relative. The closer the match of two haplotypes the closer the relationship.

 

What are its weaknesses?

Many men do not get very many close matches, a result of both the limited number of men who have taken one of the tests at this point and the ability to clearly differentiate between close, distant  and non-relatives.   The cost can also be prohibitively expensive as more STRs and SNPs are tested.

 

Many testing companies do not offer the yDNA test. The greatest amount of YDNA testing appears to come from FTDNA although their support in understanding test results can leave users with more questions than they had before testing. Take this test only if you are serious about genealogy or have no information about someone in your patrilineal line. This test is also a great test to further support or refute a relation to another male identified by conventional genealogy or by the autosomal test. In either case, this only a first step and you must be prepared to follow up and read more about the details of the testing and do further analyses (more STPs and SNPs) are often required.

Although FTDNA is a clear choice for the yDNA tests I have not found them or their website to be very user friendly..