Actually, assuming nothing is wrong with the "specimen"- most proportions are exact. My finger-to-finger span is 6'2", same as my heights. Held strait, and not curved along the face, a handspan is exactly the size of the face. Some things, such as legs proportionately compared to torso, vary from example to example. And, then there are certain hormone (especially growth hormones) that, if in the wrong quantity, alter the body shape.