Confirming a third cousin

Just recently I found a third cousin through normal autosomal DNA matching, and they also descend down a female line to a common ancestor on my female line.

Now because I have a fairly unique signature on the HVR2 part of the mtDNA,

263G 309.1C 315.1C 319C 

we were able to cheaply confirm our connection using a YSEQ HVR2 mtDNA test at only $US25.

As this is not a full-sequence test it’s not guaranteed to be a match, but coincidence seems unlikely.

The URL for this test is https://www.yseq.net/product_info.php?cPath=28&products_id=38290.

My third cousin matched on all these markers, so we know must share a common female ancestor. This ancestor is Jacoba Jansen born in Leiden.

So now I’m looking for other living descendants of my female line to see if we can verify an earlier ancestor. This is not an easy task as it requires building you family tree down all female lines trying to reach a living person. I’m finding that female only lines are pretty rare, the chance of them dying out is very high. There is also the sad fact that 18th/19th Century Leiden was a pretty unhealthy place and the death rate of children was very high.