Dose having an apple shaped body have to do with your bone structure?

Last night, I found out I have an apple shaped body. My arms & legs are pretty thin but my belly is very round & fat. My mother always tells me that I should work on exorcising a lot & when ever I do, I do not see a change in my tummy. I can't help having an apple shaped body. I was thinking that I might have a strange bone structure since my mother's & my sister's do not have a curved outward back & stomach. What is the real answerer. Is my mother right that I should exorcise more often or are my bones different?