I'm 15 years old and I hate myself, cause I'm not good enough.?

I feel really blessed that I have what I have, like my parent's don't talk to me very much but at least they're together and they don't make life hell, i live in a more than nice area, i have a 2 floor bedroom...even though i don't need two i just need a bed, my mom loves designer bags and I'm fortunate enough that she buys for me. But I have this feeling that I don't want these things, like I'm not bright AT ALL [my family is at Ivy league standard, my sister is in Georgetown and my other sister is in Harvard, my parents went to Yale together] and honestly, I don't think my grades are up there. I'm not good at sports [my brother is a trophy winning golfer/tennis player and he's like 11] and the blood that flows through my veins is rich with the blood of a National hero, Writers, Businessmen, Inventors, Royalty and Leaders. This just, makes me hate myself, that I'm not that smart, I don't even think I have what it takes to go to college and I don't have any trophies or awards to show. It's like I'd feel better about myself if I just worked as a waitress part time and go to school and fend for myself from the ground without contact with my family. Like, what should I do to get rid of this feeling and just accept everything? I'm sorry if I sound, spoiled or bratty or whatever. I think my parents know I feel bad, and they just hint that it's ok and I just have to follow my dreams but, the feeling is still there. Like, i can't do it unless I completley cut my family out.