Second cousin DNA tests are my favorites. You share enough DNA with a second cousin to be really useful for genetic genealogy. When someone matches your second cousin, you know which of your four pairs of great-grandparents they are related to, so it identifies the family line they are on.
Of course not all second cousins are created equal. Due to the vagaries of DNA inheritance some may have inherited more from the mutual great-grandparents and some less. For example, my Dad shares 608 cMs with my second cousin John from his mom’s side and only 389 cMs with my second cousin Dick from his Dad’s side. I discussed this variability in a recent post about how to tell the relationship from the shared DNA.
I thought I had no chance of a second cousin on my maternal side because my German-born mother’s parents were both only children, or so I thought. When I started researching my family history back in the 1990s, by asking questions of my aunts, I found a family secret or at least a story I had not known before. My great-grandfather Benedict Reiner had gotten the innkeeper’s daughter pregnant and then left town; he moved to Munich and a few years later married my great-grandmother. Further discussions had revealed that the child’s name was Xavier and he had visited occasionally so the families had been in touch. This was not enough information to find him or his family, since he had his mother’s surname, but thanks to GENI.com, I found them by accident. That story was a blog post earlier this year – http://blog.kittycooper.com/2016/01/thank-you-geni-com/
Now for even more good luck, my brother had a trip to Germany scheduled for a few months later so he was able to take a day off and actually meet our newly found cousins. Here is the picture.
Even more exciting for me, we convinced them to test autosomal DNA at Family Tree DNA. We tested the oldest, my half second cousin Edeltraud, the grandmother of my correspondent Katharina. Today the results came in and I am so very happy!