Who Am I???1

Who am I? Do my genetics decide?
Am I a predetermined piece of shit, or is that just what transpired?

Well I'm bolstered by the transience of identity
Don't tell me who I am
I am nothing and so are you
And that's good it's like when I speak of I, I speak of you
It's hard not to when you're just a character within other peoples lives
Who am I?