Kamon Info and search for Nakayama and Ohashi

I was told that the kamon is inherited from the mother's side. If this is so, my mother is Caucasian and my father is Japanese. Would I then inherit my father's kamon or would I inherit my grandmother's kamon?

Second question is that I am searching for the Nakayama kamon and for the Ohashi kamon. I know that the Nakayama side if from Kumamoto and that the Ohashi side is from Hiroshima. Any info would be greatly appreciated as I am trying to get in touch with my Japanese side.