Middle
Born Mary Elizabeth, when I was young they called me Mary, which I hated, because all the neighborhood kids made fun of me. (I was in a catholic school so they'd say here comes virgin Mary). So when I was about 12 I decided I wanted to be called Beth, and for months I didn't answer anyone who called me Mary. Eventually it stuck. By the time I was in high school, mostly everyone called me Beth.
Daddy now calls me Mary Beth, for some reason I don't mind it coming from him, I figure at least he's trying to compromise. Mom only calls me Mary, or Mary Elizabeth when she thinks I've done something stupid. My younger brother sometimes calls me Mary - just to aggravate- but that's what little brothers are for ;)