Why don’t people value me?

So everywhere I go, for as long as I can remember, I have been referred to as ___’s little sister. (I’m going to spare my brother his privacy) I feel like no one knows me as a person and only as the little sister. No one cares enough to get to know me, and every time I engage in conversation with someone, they without fail always ask about my brother. They also never get my name right. It’s always “Meredith, or Madelyn.” It’s freaking MARILYN. It’s not that damn hard. Why don’t people view me as a freaking human instead of just __’s little sister? I hate it.