Why is my mum so spineless? She just allows my sister to think she king of the house...soo angry!?

i feel the same way because my brother is the same way as ur sister and hes younger then me and my mom belives him more then me even thought she knows how lair he is and i hate it how he treats my brother so i know how u feel and my e-mail is caravantes_carmen@yahoo.com and ask me for my number or we can talk there whenever bbecausei also need to talk someone really bad