Simply the way our magic works. And yes, I am what they consider a "Nord" back home. We're descendants of the Atmoran people that moved south to Skyrim to escape war.
I'm the Dragonborn. When I kill a dragon, I absorb their life force into myself and their power and knowledge become mine. I try to stay true to my mentors' philosophy of only using the my power in times of true need, but I essentially use it to protect my people.