Ancestry connected me with 2 people that are siblings, (Unknown to me) .Our DNA match between me and the other 2 is 850 and 971 CM respectively. They are 10 and 20 years older than me as well.
Based on timelines and Geographical proximity to my Paternal grandparents, I'm left to wonder if my Grandfather was biologically my Dads Dad or not. My THEORY is that these 2 siblings Dad may be my biological Grandfather before he even met his subsequent wife and had children. These 2 would then fit right in on the DNA match percentage to me , the timeline makes sense, and their Dad was living in the small neighborhood of my grandmother during the time of my Dads birth.
My Grandparents only had 1 child (My Dad) 5 years into their 10 year marriage. (That alone seems odd)
I am able to trace DNA and known relationships to my Dads Moms family and my Moms, Moms family. So I do know who my parents are.
I have asked an elderly first cousin of my Dads to take a DNA test and he has agreed. Since my Dad and his cous share a grandfather, there should be some DNA connection to me and my Dads cousin. (I would think). If there ends up being no connection, how can I establish that these 2 siblings actually are the half siblings to my deceased father?. Right now besides the connection to these 2 children and that their dad was living close by to my Grandparents, I have nothing else to prove that their Dad is my grandfather (biological). Is there some other test , or something in our DNA results that would be more conclusive?
As a followup... I am a Male. The 2 siblings are 10 years apart. one Male, one female. The male to me and him match 971CM, I match 850CM to his sister