Why do I get angry easily? Take today for example

I was so pissed off at my parents today, mostly my dad. I mean, it wasn't bad that they made me work outside for an hour before I could play video games. But it was bad when my dad made me get off  in the middle of my computer time, made me write a stupid essay, and wouldn't get off for a while after I finished. WTH?!!? That's just pointless. Anyway, I should go now so I don't break the keyboard. Bye!