You know even though Steven is Italian and Dipper is...I have no idea so I'll just go with the nebulous "White" Stepper looks kinda like he's of Hispanic decent. Slightly tanned skin, super dark brown to black curly hair. I'm not trying to stir up and PC race bullshit like most of Tumblr, I just think that's kind of interesting.
Hispanic… Huh. I honestly don’t think so, though I could see how his skin coloration might be a throw off. Honestly though, I headcanon that the Pines family is of Jewish descent. So to me, Stepper looks like a mix of Jewish and Italian (a little more Italian though, if you ask me)