Why does my mom always take my younger sister's side?

Anonymous
Whenever we have an argument, my mom sticks up for my sister who is three years younger than me, and tells me I'm being mean or bullying her. That is never true because my sister always says something spiteful to me first but my mum ignores it. And now the biggest problem is that my sister has learned that she can say anything to me and get away with it, so for no reason she'll be really mean and if I say anything back at all it'll be me that gets shouted at. It's really annoying because my mum seems so blind to how my sister speaks to me, and I can barely say anything to her now without being screamed at by my mom (even when it's not an argument, because my mom assumes that the only form of interaction I have with my sister is bullying her). Any advice, it's driving me crazy!?
Why does my mom always take my younger sister's side?
2 Opinion