If you tend to pack the pounds on your tummy or your back or your upper arms, you'll continue to tend to put fat there. Forever. Sit-ups and squats can help shape our bodies differently, but no amount of diet or exercise will turn you into a person who naturally stores lipids in a different place.
Specifically, your sex hormones. Testosterone and estrogen are two of the biggest drivers of fat storage. They’re the whole reason that men and women tend to have different body shapes when it comes to chub. But it's not as straightforward as "testosterone makes you put fat in your belly." In fact, it's men with low testosterone who start storing lipids there, which is why, as they age and their natural testosterone levels decrease, they generally start getting that potbelly look. The most obvious is puberty. As teenagers hormones kick into high gear, they undergo all kinds of bodily changes because testosterone and estrogen (and, to a lesser degree, progesterone) are responsible for a lot of our secondary sex characteristics. And during this time, we also start to develop body fat in those characteristic places, men in the stomach, women in the thighs and butt. This is because adipose tissue in different parts of our bodies have receptors for different kind of Hormones. The fat in our stomachs, especially that visceral fat that surrounds our organs, seems to respond well to androgens (i.e. testosterone), and researchers think that's because visceral fat cells have androgen receptors. Subcutaneous fat, which is the stuff you develop just under the skin, has estrogen receptors. This might be part of why women start having a higher body fat percentage when they hit puberty: More estrogen prompts the growth of more fat cells.