What could i be mixed with?

I'm black.I was born with red hair like lindsay lohan's but now its like dark brown almost black and have a little red in it.And I'm trying to see what could I be mixed with.My teacher told me to write 2 paragraphs about my family history/race and my mom never tells me about it some reason.its almost like she doesn't like talking about it.But my facial features look like kerry washington (google her name if don't know who she is) except my lips are smaller and my nose is bigger.I don't have any freckles,so I don't think or know I would be irish or scottish.My facial features are really strong.My mom has straight dark brown hair and features just like me.Were both medium brown skinned.The weird thing is I look just like my mom and my sister looks just like my dad.My dad and sister look african, me and my mom do not.But she told me I got my red hair from her side of the family.What could I be mixed with?