G/F's parents are cousins?

My new g/f is ethnic Chinese, from someplace near the border of Vietnam. She told me that her parents are first cousins, She said that marriages were arranged at birth on a regular basis in their village. My g/f seems normal enough (actually has a 140 IQ). I have never met her mom and dad. What are the odds she would have some type of latent gene disorder in any offspring she might have? While I am not personally repulsed here, my buddies g/fs gave me a resounding "eeewwwwww". I love her and am thinking seriously about marrying her.