Is it normal to like girls that are not my age

Ok well Something I have noticed about my self is that I typically like Girls that are like 16 and even as young as 14 (I just turned 18) and sometimes I find that I'm attached to girls that are like 20ish and not just because of there looks. I like there personality and I just don't see girls my age the same way I see them almost as a sister. Is that normal?