Shiny is so right.
Actually, even if you have the right WH ratio, you'll probably still get muffin top unless your stomach is hard and flat as a board. I am 27/37 but I am super short-waisted, so the vertical proportions on jeans are never quite right for me and end up pinching. When I lift my arms up and stretch my torso, I am able to fit 2 hands between my bust and waist...which according to Imogen's theory, would be normal--neither short nor long waisted. It is amazing how much thinner I am just as a result of those few extra inches that allow just enough space for the little fat I have to distribute itself.
Then as soon as I put my hands back by my side, everything compresses back to its former flabby glory. Sigh. But it made me realize there is nothing I can do about it. There just simply isn't any room in that area, so even an ounce of fluff is going to look more like a pound. I was flabby even at a 25" waist.
For me, muffin top has nothing to do with being fat, having kids, wearing the wrong size or fit, or not wearing a high enough rise. I have 10" rise jeans that give me muffin top and I am a size 4. Never had any babies. For some reason, pants don't seem to do this and I haven't quite figured out why. Skirts and dresses skim over everything perfectly, so if there is ever a day when you are feeling low, I recommend ditching jeans and pants and wearing a pretty dress instead.