My mother and my grandmother are trying to stop me from finding out my families history?

I started working on my ancestry on my grandfather’s side for a project for my school. But, when I started on my 90-year-old grandmother’s side, she clammed up and tried to stop me. She started crying when I asked her questions about her family tree, and I thought she was crying because she missed her folks. Ha! It turns my grandmother is really a bigot, which disappoints me. She isn't white enough for her liking, and neither am I, I guess. Her grandfather was a black gentleman from the States, which I find very interesting and not at all off-putting. Now, she's embarred because she ped for white all her life and wanted it kept that way. Who the heck cares in this day and age? She wants me to quit but I want to go on? Do I owe her that "respect" as she calls it? Now my grandmother is upset with me, my mother says I shouldn’t go on with it. I don’t know what to do I really want to know my family history. I’m in the 8th grade.