I don't think it's a touchy question as long as we can talk about it like adults.
As for me, born and raised on an Indian reservation in upstate NY, I'm 3/4 Akwesasne Mohawk, 1/4 French. My mother is half French, half Mohawk, my father is full-blooded Mohawk. I speak the language (less than 2500 of us do now), and of course, recognized by the BIA (Bureau of Indian Affairs) as an official member of the tribal rolls. My family still lives on the reserve, and my grandmother and great-aunt are tribal elders (the Mohawk are a matriarchal society in times of peace). My father moved off the reservation, but lives only a few minutes' drive away.
I've moved to NJ in the early 90s, and joined NJIPMS. Those guys are some of the best friends I've ever had, and they run the full ethnic gamut, Irish, Polish, Israeli, Russian, Czech, African-American, Chinese, Japanese, Korean, and some are just plain old mutt Americans. Down to the last man, they're all great people who share a common hobby and interest.
I don't think that ethnicity plays as big a part in the hobby as we think. That being said, I think the hobby is passed down from one generation to another, so if your father was a model builder (or older brother, etc) chances are you probably picked up on the hobby too.
I do know for sure that there's absolutely NO DATA whatsoever on the cultural backgrounds of modelers, median incomes, ethnicity percentages, etc.
I've been dragged through this hobby for 30 years now, and I've never heard of any conflicts within the hobby due to race, ethnicity, etc... I've seen alot of conflicts over whether a paint color was correct, though!!
Jeff