Thanks guys

She's 20 as of today.

My mom lets her behavior happen. She gives her what she wants. So I guess you can say that, in a way, she does encourage the behavior.

My dad, on the other hand, is a bit sick of my sister like I am. She really is a brat sometimes.

My sister doesn't really talk much to me anyways, so it wouldn't be the end of the world if I got rid of her. She only seems to talk to me when she wants something.