I get blamed for everything my little brother does. Why?

Today I built an awesome club house. I invited my older brother (David) and younger brother (Jonathan) be the President and the Sectary. They said ok. Then, my pest of a little brother turns off the lights and i can't see a thing. I was waving my hands around inthe air trying to find the wall and they acedentily slammed into Jonathan. He punched me. Then re ran to my dad and told on me. I told my dad that Jonathan punched me, and it was an acident when I hit him. My dad did'nt belive me and sent me to my room. I wasent allowed to go into MY clubhouse and I got grounded for a week. And David who is my best friend won't talk to me and also blames me.Things like this have happend before. Is it because I'm the middle child? Or because I'm older than Jonathan? Why do my parents always blame me when I did'nt do it?