From memory for some people hip bones have the potential to grow if they are really lucky until they are about 25, for others they fuse earlier, anyone starting in their late teens still has a chance of getting feminine hip bone growth, i think its a case of ymmv to a point here, over 25 and i think forget it you just have to hope for some decent fat redistribution, if there where some pill for changing my skeleton i would take it, i am however lucky that for a guy my hips are pretty girly, i have actually always stuggled finding trousers that fitted until i started wearing girls jeans, my current hip to waist ratio is average for a girl 