My parents used to compare me to my older sister who was a genius. She got a 4.0 all thru school, which totally TICKED ME OFF!

Not everyone is a genius. Not everyone can get a 4.0 all thru school. My parents should have realized that, but unfortunately they didn't. They just thought I didn't study enough, or I wasn't trying hard enough.
The truth was I just had a hard time in school. Math and I did NOT get along. I couldn't understand Algebra, and when my Dad tried to help me with it, he got upset and angry, because He understood it so well and it was SO easy for him, he couldn't understand why I couldn't get it. It was the same when my sister tried to help me. She'd get short with me too, and just give up. I asked my teacher to help me, and he said "If you didn't get it the first time, that's too bad." How's that for a teacher!
Sit your Mom down and TELL her you NEED to talk. Then nicely ask her not to compare you with others. Tell her that you're different than anyone else, and that you ARE trying very hard -- that a 3.5 average is EXCELLENT and she should be proud!!! Very few people can get as good a grade as you are getting! But just ask her to stop comparing you to anyone. You are YOU. And you're a GREAT you!!! God bless honey and best of luck. Let us know how things go, will you? Hugs, Lee