I searched on google but i dont found a decent answer. Google sucks.
I wanted to know: If a person has dual nationality, for example, Brazil and United States, and both go to war, but I live in Brazil but I was born in the USA, to which country should I follow?

If both enforce mandatory draft, you'll probably be drafted in the country you live in.

Pick the country that's going to win

Like me Im Mexican but live here. Americans hate me but I live here and I support it.

None. If you're not sure which country you want to win, there is no reason for you to risk your life.
I mean first you risk your life and then even when country that you supported wins you're not fully satisfied with that.

Thanks guys.
I'll close.