DNA testing has been around for a long time and the general public probably thinks of uses such as: paternity testing, ancient anthropology, and forensic science.
In about the year 2000, DNA testing for genealogy began to be popularized when Family Tree DNA began offering tests specifically for that market. Then in perhaps 2007 Ancestry.com either began or improved their DNA test marketing. At that early stage they were offering Y-DNA tests. To understand all this it is important to understand there are 3 main types of genealogy DNA tests. Y-DNA (usually you must choose STR or SNP markers though STR is more common for genealogy purposes), mtDNA, and autosomal DNA.
In 2008, I took my first DNA test, the Ancestry.com Y-DNA 33 STR marker test. I came up with 2 close matches that were both surnamed McCormick just like me. Because Y-DNA goes father to son only, it follows the straight paternal line and having a McCormick match is precisely the surname match I would have expected. We began to email each other, but because of the difficulties of Irish genealogy we have not been able to document our cousin relationship. I also found out that my paternal line is in haplogroup R1b.
mtDNA was not quite as developed as Y-DNA at first for genealogy, but in 2010 I ordered my first mtDNA test. My matches with that were not particularly useful for anything, but I found it interesting to know that my straight maternal line is in the H haplogroup.
That same year I also got Ancestry.com's upgrade from 33 STR markers to 46 markers for my Y-DNA test. I still matched the other two McCormicks on my list exactly, except for one marker.
So far you may be thinking, "Why would anyone take a DNA test when all they get is this?" Well, some people don't think it is worth the money. That is up to you, but I am all for using DNA to help with genealogy. I look at is as a long term investment for a few reasons. 1) As more people test, more matches may appear. 2) The money we spend on DNA testing helps these companies stay in business and therefore funds progress in the science. 3) This may help others who are adopted or otherwise will benefit by seeing you as a match when they test.
The next tests I took were the autosomal DNA tests with Family Tree DNA and Ancestry.com. I will discuss those next.