Mrs. was adopted and wondered about searching for her birth parents all her life. She knew what hospital she was born at and was told that her mother was only 17 yrs old. That was it zip else. Well she had a DNA test done that showed up two third cousins with several names overlapping between the family trees. In three days I narrowed down the common great great grandparents and worked the tree back to everybody. It took 4 days for me to narrow down the facts to her father. Found her father on the left coast, and that he had past away a few years earlier.
Tips, get a DNA test through a place like Ancestry.com. Then when the results come up, check the closest DNA matches' family trees. Now comes the tedious part. For third cousins, you share the same great great grandparents. You have 32 great great grand parents, 16, on Mom's side and 16 on Dad's side, (with some occasional overlap) That means you have a lot of their ancestors to sift through. Ancestry will permit you to see who also matches you and the other match. Check their family trees for common names. When checking my wife's matches' trees I found two names in common for many of the matches. So I started a family tree beginning back at the GGGG grandparents and then worked forward. When I came upon an entry marked "private" I looked up the parent's obituaries for surviving relatives to fill in blanks. Then I went to internet searches and newspaper archives searches for living people. My wife has two brothers and two sisters listed in their father's obituary. By checking facebook (even with privacy settings), sites like been verified, Linkden, etc. I was able to see about how old they were, where they lived and even the names of their children and relatives. The fact that I can do this from my desk is both scary and gratifying.
In the search for my wife's mother, we are still looking. The closest DNA matches on the maternal side are 4th cousins, which means comparing great great great grandparents. That means searching through potentially 64 GGG grandparents. Some of the family trees posted did not even go back that far. So I had to do the research and complete the family tree of some DNA matches back to GGG grandparents, find common names and then begin working forward. As it is now, I have located four most probable of the 64. Of the total 1,059 DNA matches, approximately 60% of them related to the father's predominantly Catholic side. Of the remaining 400+, those two sets of GGG grandparents can be traced down to about 35% of the remaining 400+ matches. I am still going through the work of extending the family trees to find other common relatives. But since, Ancestry reports DNA matches to as remote as 8th cousins, I could have ten thousand people to sort through. I devote an hour or two every day to sorting though things and hope perhaps one day a closer relative will come up as a new DNA Match.