Why won't my hair curl at the sides and the back?

I went my entire life thinking my damaged curls were just waves and massive frizz. Had my first curl cut recently and had all the chemically straightened hair chopped off- meaning my hair had to be cut very short. The top of my head is like a massive mop of curls on the entire top portion when I apply gel after washing. From about an inch above ear height down though, there is no curl at all. The entire back of my head has no curl either. The hairdresser said that those hairs are 'too short' to curl and not to worry because the curl will come out as it grows, but I'm worried it won't. Some of those straighter strands are the same length as the strands toward the top of my head that do curl by raking my fingers through it. It just seems strange to me. Do you think the curls will come out? Maybe they're just bigger curls and not as fine as the ones on top of my head so I can't see them yet? I don't think I've ever heard of anyone experiencing this. I know people can have combination hair- even some of my 'curls' on top are more like weird waves that have a slight spiral, but to have all curls on the top surface and straight everywhere else? It just don't seem possible to me...