Check out the heels of this baby
I have small feet (relative to my height)... if you know trigonometry, think of a right angled triangle, the heel being the opposite and the foot being the hypotenuse, you can see that the angle of elevation is greater for people with smaller feet. So it's physically (or rather, mathematically) impossible for me to wear, say, 5 inch heels. Whereas someone with larger feet would be able to.