Both of my parents are on Facebook, and I'm friends with them too. I never posted much to begin with, so it doesn't affect me too terribly. My dad doesn't really use it, and it's not even under his real name, so it's not so apparent (pun unintended, but welcomed) that he is my dad to most people. I'm pretty sure my mom's face shows up on my Facebook page more than my own face, because she always tags me in everything. Whenever we go to the movies, the does a check-in and tags everyone. At the airport? Same thing. Concert? Yep. Dinner? Yeah. The list goes on and on. It doesn't bother me too much since it's been going on for so long. The only thing that gets on my nerves is just how often I've had to explain how to do random things on FB to my mom because she's a but technologically challenged and considers me a better computer expert than my dad (who has a degree in computer science) for some reason.
My bigger problem is with my extended family on FB, truth be told. They have a bad habit of making deceased relatives their profile pictures, commenting your friend's post on your wall as if they're writing a post on your wall instead, sharing the most obnoxious hyper-religious content you can find, not to mention all those FB game posts and updates. They're even more tech-challenged than my mom, and know nothing of proper "how not to look like an ass on Facebook" etiquette. It also leaves me in an awkward position, because many of them are from a very conservative part of the US, and while I know that they are kinda racist, I have no idea how homophobic they are. I always wonder if my 'likes' show up in their feed, so it always makes me antsy to even just "like" some post that's related to gay rights at all. (I also find myself too paranoid to 'like' anything related to my own sexuality because I'd rather not be approached about that topic based on something like that).