Yet another question with not enough information to give a viable answer. What kind of scars? How many scars? Scars from what? Where are they located on your body? How long have they been there? How old are you? What is your gender? See what I mean? I just gave you seven different scenarios that would require at least seven different answers to your question. Oh, did mention self cutting? Fires? Blunt trauma? Explosions? Etc. Etc. Or, if you're of a creative bent, seven different ideas of how to develop the main character in your new fabulously popular novel.