Why do people call me a Oreo?

I find this stupid. I get this from my cousins alot sonething like "you aint even black," when I ask why, they say cause i talk white. I guess I phrased the question wrong. I know why but why do people say that? It's stupid. And it's not like I don't I've pride in my self the way I look or my people cause I do. But I also know that today Ebonics is something u just can't Go around saying otherwise ur viewed as uneducated. Sad but true. So why am I criticized for trying to gy somewhere?