I am half Montagnard, but what is my other half

I would like really to know what I am mixed with. Now I know I am from Vietnam because I have scars left over from all the battling. I was born in 1970 and adopted over to America in 1972. I look black, everybody states that I look like a light skin black. Some people can see some oriental features in me. It states that I am Montagnard, I don't know. Maybe I am mixed with black. My hair is wavy and dark brown and my skin is lighter that an Montagnard but darker that a vietnamese. I am looking for anyone who may be able to help distiguish my identity. Maybe if my father was a soldier I could find him. Don't know where to start, CAN ANYONE HELP ME.

Tran Se Ngoc Bich (that was my name in Vietnam)