So I posted recently because I did an Ancestry DNA test which came up with a lot of matches with the same surname. Due to the privacy of the other family, I'll say their name was Smith. Through working with numerous 2nd and 3rd cousin matches, I was able to find a common ancestor, someone who would be my 2x Great-Grandfather. It transpires that this man's son was my Nana's Mum's best friend, let's call him John Smith.
Nana did an Ancestry test and her results have come back. Her top 5 matches, not including me, are from the Smith family. The other top matches we don't know, but my Nana's Mum was illegitimate. Anyway, we initially thought, right this proves it, her Dad was John Smith. However, I did some digging and Nana has 5th-8th cousin matches that show up as sharing a common ancestor on her Dad's (who she knew growing up) side of the family.
I know this is Ancestry trying to form a relation. However, it's now got me thinking. I'm now wondering if there is perhaps a chance that 2x Great-Grandfather Smith is the father of my Nana's Mum, actually making him my Great-Grandfather.
I looked at my top 2 cousin matches on MyHeritage (waiting on Nana's upload results). Person A is 191.5cM and 8 shared segments, and is the grandson of 2x Great-Grandfather Smith. Person B is 143.7cM and 4 shared segments, and is the granddaughter of John Smith. I would have thought that I would have a higher cM to the granddaughter of John Smith? Or is it just because I share more DNA with one than the other?
On Ancestry, Nana has 404cM across 21 segments and 302cM across 11 segments with the grandchildren of 3x Great-Grandfather Smith, who would obviously be her Great-Grandfather if John Smith is her Dad.
Could anyone please offer any help with this? I'm sorry if it doesn't make sense, I struggled with finding an easy way of explaining this. Thank you in advance!