if you played Mass Effect 1&2, your character made several choices
if you are starting a new character in ME3 rather then importing your characters from Mass Effect 2, now you get the chance to make those choices
You can choose whether you were born a colonist, on earth (earthborn) or in space (Spacer)
You can choose if you are a war hero, ruthless, or sole survivor
you can also choose who died and who survived: Ashley, Kaidan, or numerous
see the Mass Effect 3 Character Creation Guide
