stretch marks on boobs

i’m 15 at the moment and i’ve been having my period since i was 11, meaning i started developing early. i was just wondering if it’s normal to have stretch marks on my boobs. im not overweight or anything so i don’t know why i have them? (my friends told me overweight people usually have stretch marks as opposed to thinner people). is there a way for me to get rid of them, or will they fade on their own? none of this was meant to come off rude, i’m just curious.