I'm losing my hair Am I going blad?

I'm currently 20 soon to be 21 in a matter of weeks. And I noticed that I have 2 patches of hair missing about the size of a quarter. I never even realized until my sister noticed it while I was sitting down. The hair around the patches grows but not the patches so I'm not sure if I'm slowly losing my hair overtime or is it just a natural occurrence. It just seems odd to me because all through High School I had long hair. I'm also wondering if it could be hereditary because both my grandfather and father went bald around their late 20s early 30s. So idk but any help would be great.