Have you got any photos?
When you wear them they will take on your body shape & your way of life. When you walk, sit down etc will effect the way the jeans wear. Things in your pocket such as mobile or wallet even effect the jeans. All these things will show creases, fades etc as these are the areas which are 'worn' the most. Alot of the artifically worn jeans which have whiskers, sand blasted areas etc are made to look as thougth they have been worn for ages.
My guess is yours have taken on 'your body/way of life' and so the creases are due to you.
Photos would be better - so we can see exactly what you mean - if no photos describe how they look & the area they are in. What type of jeans, washed (how much so) or raw?
It could be the way they have been stored by you or the shop.
You could try using starch to stiffen it - but I imagine it is due to you & the jeans taking on the way you wear them.
It could be something TOTALLY different!

Get those photos up Prada!
