Past injuries, lots of those.
Jumped into a glass table when I was around 4 or 5, glass pieces all over my legs, no deep cut or anything serious though.
Landed on a rock right to the head when I was 2nd grade, I don't remember how it happened. Blood gushing out like a waterfall dripping to my face, and that's how people called me red irl (which sounds cool, so I'm not complaining). The scar is still on my forehead.
Accidentally stab myself on my left hand, it left a small scar.
My blood coagulation system is abnormal, I dunno what they call it scientifically but it makes all deep injuries not to recover normally, instead of restructuring like a skin it will form a lump instead. Means every single cut on my body will turn into a scar.