When my grandma's sister passed away around the time my mom was 10 (this was 1982), her husband decided to not really speak to my grandma's side of the family even though my mom and grandma had a really good relationship with their kids (my mom's cousins) and they didn't really communicate with each other as much, and two of their kids ended up becoming pretty well known (one is a chef and the other does stuff with MSNBC) so now I have famous relatives who I only met once when I was 5. They live far away from me and I'm pretty sure they have no idea who I am, and my grandma's sister's husband lives in my state like 30 mins away from me and runs a doctor's office but I have never seen him in my life for the reasons mentioned above. So yeah I have a whole side of my family I don't really know at all. It's also crazy how my mom just casually told me this.
Through that grandparent I'm also related to another bunch of well-known people who came from a town/city in Slovakia according to ancestry.com (back when it was called Austria-Hungary) who likely have no idea of my family's existence but that's a whole different story