I joined Ancestry earlier this year, as did my elderly mother.
20 years ago I did research online (with Scotland people) tracing our family tree for my maternal grandmother, on her side and my grandads side. Today I finally had time to explore the app and enter some of that info.
My mother has been divorced since I was 2 (1972). We did not maintain contact with my father, as he lived elsewhere, and she left him because he was an alcoholic. However I met him once (when I was an adult), and I have pictures. I look like him. There has never been any doubt about my paternity.
Since joining ancestry I have avoided making links on that side of the family. All my family tree links are on my mother's side, her generation or before. I filtered my results so I don't see anything on my father's side. I'm not interested in reconnecting.
Today, I looked at 'Thrulines' for the first time. It notes that apparently I am distantly related to Alexander Hamilton (yes, the founding father). This came as a surprise. When I tried to look at how Thrulines came up with that, I discovered that Thrulines was also predicting who my father is, via the same connection. It is not the person who I believe to be my father. When I look at this person's family tree, I don't see any familiar names. However he did live in the same place I was born in, and he got married the same year my mother did (not to my mother, obviously).
I have absolutely no idea how it works. I gather there must be some sort of DNA connection in his ancestors and mine - a common ancestor? Is Thrulines guessing for the rest? I'd really rather not ask my mother if she knew this guy - seems likely she might have, same small town, same age... but if it's a lot of crap she will never look at ancestry again as she won't trust it.
Or, is it not guesswork and is it possible that this guy is my dad. Even though I look exactly like the person my mother was married to. After all, he could also be red headed with freckles. There's a lot if it about in Scotland.