I actually get asked this quite a lot, and when I ask why they say because of my skin color and hair. When my hair was long and straight I was asked if i was Indian. Now that it's shorter and curly people ask if i'm mixed.
In my earlier years I was somewhat of a lighter skin tone so i got asked in grade school a lot.
But sometimes it offends me by the response I get when answering the question.
"You HAVE to be mixed black people just don't have hair like that"
"Why would you lie?"
It get annoying very fast.
Both of my parents are african american.
Therefore so am I.