Is it normal to have so much anger towards my sister?

kids are annoying little fucks that's for sure!

This can be verryyy normal! I have a twin brother that is completely opposite from me and we are ALWAYS fighting! We never agree on anything and we are always screaming at each other calling each other bad names and physically beating one another is the usual thing now lol ... Your normal

(sometimes I hate technology). 1: you are responsible enough to be in charge & make decisions.
2: you care about her. This will make you 'family'.
Correct her when she is disrespectful. Once you have done all this, she will be more to listen to you when you correct her. Let me know if you have any ?'s. I wish the best for you. Again, good luck

Apologies, I forgot about YOUR dilemma. You're her sister, not her mother. However, you are an adult, which makes you a parental figure in her life. Like it or not, YOU are teaching her how to behave around your mom, & as an adult. You are an influential figure in her life. You must be careful how you interact w/your mom around her. Don't question your mom's authority, integrity, etc. around your sister.Don't allow mom to fight w/you in front her. If mom insists, ask her to another room & try to resolve it quietly. Being her sister, she sees you as an equal, so, if you do it, so can she. You need to let her know (& mom separately), you won't tolerate unacceptable behavior towards mom. Don't stoop to her level. you are superior in the pecking order. She should know that. Take her out & do things w/her. This will show her 1:

Obviously your mother is not a disciplinarian. At least, not anymore of she once was. Standards and consequences are not enforced. Raising children is very hard. It's tedious, and painful at times, and your mother already raised one child. One thing I've noticed, as parents get older( ESP. If they have adult children) is that tend to take a 'grandparent' approach to children. No consequences, forgive everything. It's easier. Child rearing is tiring, & they don't have the energy they used to. Your mom may also let her get away with things out of guilt for her situation, the fact that she had no parents. No matter the situation, children need boundaries, consequences, routines, & consistency. Children are very adept & quick to learn how to get what they want. I crying gets them what they want, that's what they will do. The parents must show them what it takes for them to get what they want. Your mom probably won't change from what she is now. But there is something that can be done. Child psychologists & counselors are very good at helping parents & kids live in harmony. It doesn't happen overnight, but you will notice a difference in a couple of months. If you can convince her to take your Sis to a counselor, I can almost guarantee life will be better for everyone. Good luck

beast

My sister was once four years old too. I was five years old and still wish I was nicer to her, even though I was pretty good. If I was 26, and hadn't learned to accept a four year old girl, I'd be looking at myself with a fair old measure of disdain. Although maybe I'd be posting on IIN about my inability to love someone and do the best thing for her.

I'd probably be the same, I hate kids too.
I don't think I'd actually fight with them though.