When you start talking about the known knowns and the unknown unknowns, you're thrown into a crazy meta-level discussion. Do I know what I know, do I know what I don't know, do I know what I don't know I don't know. It becomes a strange, Lewis Carroll - like nursery rhyme.
So many American plays are about family. When you're in the first part of your life, you write about family a lot. I find with my absurdist plays that I was actually writing about my family, but so disguised I didn't realize it myself.