There are three basic types of DNA testing:

Y-DNA testing which examines the Y chromosome and gives males information on their strict paternal line - their father’s father’s father’s father’s father’s…father.  In many ethnic groups, the surname has also been passed down the paternal line.  This makes Y-DNA testing very useful in determining birthfather surnames for male adoptees.

Mitochondrial DNA (mtDNA) testing for males and females which gives information on the strict maternal line – your mother’s mother’s mother’s mother’s mother’s mother’s…mother.  This is not the X chromosome.

Autosomal DNA (atDNA) testing for males and females which examines some 700,000+ markers on your 22 pairs of chromosomes plus your X chromosome(s).

For males usually anything less than Y-DNA37 (37 markers) is essentially useless in identifying a paternal surname. Males should have done at least Y-DNA37, preferably Y-DNA67, unless they only have a few matches at a lower level.  If you already have done Y-DNA12 or Y-DNA25 and you have a number of matches, you should upgrade to at least Y-DNA37. 

Males should also do their autosomal DNA ("atDNA").  The three companies for this key test are AncestryDNA, Family Finder at FTDNA; and 23andMe.

Females  should do their autosomal DNA ("atDNA") The three companies for this key test are AncestryDNA, Family Finder at FTDNA; and 23andMe . 

Many people find the AncestryDNA test helpful in identifying matches’ families.  It currently does not have many of the tools that DNA “veterans” have gotten used to, such as a chromosome browser function which is helpful in determining shared chromosome segments among your matches, a good indicator of common ancestors.  It does provide the raw data which you can upload to http://www.gedmatch.com to see those DNA segments. The best scenario is to test at all 3 companies, if it is affordable, and upload all raw data to Gedmatch.  Gedmatch is a FREE, non-profit, “do-it-yourself” genomics website that allows DNA testers to upload raw data from FTDNA and other companies to compare with a large database of data that has been voluntarily uploaded by other testers.  Most of your matches from 23andMeFTDNA and Ancestry will not be there but the tools there are extremely useful.

For both males and females, all three of these autosomal tests provide the raw data which you can upload to http://www.gedmatch.com to see those DNA segments. The best scenario is to test at all 3 companies, if it is affordable, and upload all raw data to Gedmatch.  Gedmatch is a FREE, non-profit, “do-it-yourself” genomics website that allows DNA testers to upload raw data from FTDNA and other companies to compare with a large database of data that has been voluntarily uploaded by other testers.  Most of your matches from 23andMeFTDNA and Ancestry will not be there but the tools there are extremely useful.

We have found that Mitochondrial DNA (“mtDNA”) is not really helpful because it's usually much too far back (1,000s of years). For adoptees, it will be rare to find a match to your biological family in recent generations using only mtDNA.  If you wish to have your mtDNA done you should have the Full mitochondrial sequence ("FMS") done. It may help in determining your ethnicity.

Adoptee Project at FTDNA The adoptee project at FTDNA is called the “Global Adoptee Genealogy Project”. This gives the administrators visual access to your DNA results if you need help.  A Welcome Letter is sent to all with recommendations and suggestions.

You can also get discounts on DNA tests through the project. To access discounts on tests at FTDNA, join the project and then go here for the discounted prices: https://www.familytreedna.com/products.aspx?Group=Adopted.
 
To join a project, log into your account, at the tab at the top “Projects”, select “Join a project”,  in the search box on the next page put in “adoptee” and the project will show in the listing.  Click on it and click on “Join”.
 

Important Warning: The tests you can get from drug stores or from companies other than the 3 mentioned here are not reliable as they only measure a very small number of SNPs compared to 700,000+ SNPs measured by an autosomal test.  They can also be even more expensive, running several hundreds of dollars.  In addition, the results from them and forensic type tests are not comparable with those from FTDNA, 23andme and AncestryDNA.

If you have known living biological relatives (such as you know your mother, but not your father, or a half sibling) additional DNA tests should be done on those biological family members to help in possible phasing of your data (analyzing and recognizing the segments that are maternal vs. paternal) and possibly see which side of your family they match.

Once your test results are posted, you should download your raw data and upload to Gedmatch (http://www.gedmatch.com). Fishing in multiple ponds is better than one. Additional information and instructions to upload to Gedmatch can be found HERE

Summary

The theory is simple - Find your DNA matches; Find others who match people on your list of matches by comparing chromosomal segments and overlaps; Find the ancestors of those matches; how they connect and work ancestral trees both linearly and laterally with the ultimate goal of finding your place in that family.

The execution is hard work, complex and tedious - but it can be done.  It has been done! We have success stories every week.