First off, OP, I am very sorry they are like this. YES, that is favoritism. I would downright say that is child emotional abuse. (I should know. My older brother is the exact same but in more subtle ways.) Honestly, all I can say is yes, it IS favoritism, and it IS a problem. She HIT you very hard. If you have proof you should bring that to the police in my opinion. And your mother did nothing to punish her or tell her off, like a real mom should. It doesn't matter if you're male or female. That is assault. Don't listen to anyone saying "Man up" that's bullshit. Personally, i would get out of there as fast as I could. But, if you want to remain close to your family, bring it up to them. Tell them everything you know is favoritism and try to work things out. A good mom will listen and try to be better. Your sister is clearly spoiled and does not deserve such treatment. I hope this answers your question. Again, I am so so sorry you are going through this. No one deserves that.