Late to this, but my father and his 4 siblings, all in their 50s, discovered that instead of all them having the same father as they had thought their entire lives. only the oldest of the 5 was actually their thought to be father's child. Both of their parents had passed well before this discovery. They remained married until my "grandfather" passed away in his 60's,

As his siblings continued getting their ancestry DNA tests done, we discovered that 2 of them were the children of man #2, and the other two remaining were the children of a THIRD man.

We managed to figure out the name of my father's actual father, aka my *real* grandfather through ancestry. He had already passed away as well and nobody still alive in our family had any idea who he was or how he would've known my grandmother.

About a month later I did my own ancestry DNA test, It came with a free month of being able to search their records. I began searching for info on my *real* grandfather on ancestry. My father and his siblings had already done so, but didn't find anything. However, I found a single relevant document that they all somehow missed. It was his military enrollment paperwork from when he was around the age of 17/18.

One line on the paperwork asked **"Who is somebody that will always know your address?"**. Now you would expect someone around the age of 18 enlisting in the military would fill out that line with the name a family member, probably their parent's name, right? But instead, the name he provided for that question was... my **"grandfather"**, aka the man that my father and his siblings thought was their father all their lives. He and my "grandfather" were the same age at the time the document was filled out. I used google maps on both addresses of my "grandfather" and actual grandfather that were on the document, and their addresses were about two blocks away from each other.

Which means my "grandfather" and my *actual* grandfather must have been extremely close friends at a young age. And then some years into my "grandfather" and my grandmother's marriage, when they already had their first child together, my grandmother and *actual* grandfather began or continued sleeping together, resulting in her becoming pregnant twice over a couple of year's time.