It figures out what part bothers you the most and makes sure that part stays fat.
Seriously, though, there's some connection to the more crucial body functions. Women tend to collect fat in the hips and thighs because that's the easiest area for the body to access during pregnancy. Evolutionarily, it's vital to have fat where you need it to keep the reproductive system running and nourish a fetus. That's part of the reason also that women tend to get more belly fat after menopause (and men always tend to carry fat in the belly rather than lower)-- if you're not going to get pregnant, you shift the fat stores to the belly where it's easier for your own body to access it to nourish you if there's a famine. The face and hands thin out first because there's no real need for much fat there. It doesn't help you survive, so your body doesn't mind letting it go.