GSK was found because one of his third cousins had their DNA on GEDMatch. So, someone he shared a great-great-grandparent with. Based on GSK's age, that could m

GSK was found because one of his third cousins had their DNA on GEDMatch. So, someone he shared a great-great-grandparent with. Based on GSK's age, that could mean the DNA uploader and GSK had a single common ancestor who was born in 1845.