Realist artists use common body-segment ratios to make a lot of their work look more real (or to exaggerate certain features if they make them different). If you can find an art book (or website) that delineates what those ratios should be, you will have an idea of whether your body segments are outside of "normal." I doubt anyone actually has all normal proportions, just that most people average out to "normal." Or you could just have an experienced coach look at you and tell you that you have a short torso and stubby arms (thanks, Rip... haha)