Probabilities

 

Possible relationships. MyHeritage.

Using several of the shared matches who appear on both MyHeritage and AncestryDNA from my Dad's results, I'm looking at the generation of connection to determine how we're linked to the James O'Brien cluster of matches in Allegheny County, Pennsylvania. The chart above shows the probability of possible relationships between my Dad and EM. She is a descendant of James' son Daniel F. O'Brien and has 72.9 cM in common with my Dad's results.

While I still think we have in common a 4th-great-grandfather or sibling of my 3rd-great-grandfather John O'Brien, it's interesting to see another possibility is that James was a son of John O'Brien through an earlier family, before John settled in La Salle County, Illinois. I have a huge gap in John's timeline. He was already in his mid-50s when he met Bridget and started a family in La Salle. As it is unclear where he was between 1831 and about 1850, there's a reasonable likelihood that he had another family in Pittsburgh, or somewhere else, before making his way to Illinois. I'm going to try to compare the generation of connection graphs for others in the James O'Brien cluster and see if that helps.