I think my mom has learning disabilities?

My mom is 51yrs old and she sometimes acts very immature and instead of just talking with me she likes to take jabs at me and tease me all the time. She is always depressed has had a horrible life and is not a very happy person yet she feels like everyone has done this to her and she has only tried to help others and has been walked all over. She is classic victim mode. Sometimes I think she has learning disabilities because my older sister and at 35yrs old my sister acts like she's 16 most the time and my mom kind of acts the same by crossing the line with jokes and seems to be only comfortable interacting with me as long it's a jab or tease.