Can your twin sister sing better than you and play the flute as well?

Who is to say she's prettier either? That's completely subjective. A lot of the famous women that guys go crazy over I think are completely unattractive.

Just remember she is doing all this making fun and bulling to feel better about herself, she is using you to fight her own insecurities. Let me tell you, i've known some beautiful women in my time and most of them are way more insecure than your "average" girl (by society's perception, all women are beautiful in their own way).

Don't let it get to you, she's got issues too and is no better than anyone else.