Ever since I was around ten years old, I've gotten sudden urges to punch, hit, or kick my peers. Not because I was provoked in any way but because I felt like it. When I turned 13, I promised myself that I would never act violently towards anyone no matter what (because it had caused my peers to think badly of me). I've broken that promise a few times but I've kept myself under control for the most part. However, since about last year, I've found it more difficult. Just by looking at someone, I get the urge to swing at them. And I'll do it but purposely miss their face by about a centimetre so they're not actually hurt. I've even punched toward my pet (a small dog) and my step-sister (a six-year-old). My sister (13 years old) has gotten so used to it that she doesn't even react anymore.
I'm wondering if anyone has an idea what might cause these urges. Though I do feel violent when I'm angry, these urges are completely unrelated to anger.