Such a bottom

I wonder sometimes how I ended up being such a bottom. I absolutely love getting fucked. Is it physical? Do I just have a super ass that can take almost any dick (or two) and ride forever. Is it psychological? Have I just always identified with the dude in the porn who is surrounded by 5 tops who are jockeying to cum in his butt? I think about it because I bet it will help me be a better lover, better able to understand how my mind works with my body.