I'm about as straight as an arrow, but I am of mixed race and I've been in both a lower income multi-ethnic school and a high/middle class predominately white school during my formative years. Honestly I never noticed too much of a difference. Kids are kids and people are people, in my estimation. It's honestly as simple as that. If you write your character as a person and not a caricature, you should be fine. 

I am glad this thread was made, truthfully. It irks me some people are afraid to write as colored people or people of a different sexual persuasion. They're afraid because people do call others out on stereotyping, sometimes rightly, but most of the time in poor taste in my experience. For instance, I do remember a female friend of mine reading some writing and telling me that 'women don't like X in bed' whereas my sexual partners have asked me to do the very things my friend said were a no-go. And people who criticize your writing will act like that often. 

My point is, people have unique experiences. Your sex, gender, sexuality, or race might change a few minute details about your life (depending on the severity of your society, of course). But at the end of the day, they're just small parts of your greater identity. If someone wrote about either of my parentage's experiences, even if I or they hadn't experienced said thing, I wouldn't call it wholly wrong per say. They have just as much right (and chance at being correct to someone's view) to write a character that way as I do writing for a 13th century mongolian protagonist.