My brother is a racist, ignorant, narrow minded bigot. He has married an equally vile woman. I have gone no contact (except when we're in the same room at family events, we are civil in these situations) for the last few years.
My sister is arrogant, self absorbed and entitled. She needs to feel superior to everyone else in some way (she likes to be smarter than anyone else, and usually is - she has a genius level IQ) in order to feel comfortable. She needs to point out her superiority as well, it's not enough for her to simply feel superior. This makes her difficult to spend time with as you are constantly defending yourself - your thoughts, ideas, opinions, appearance... everything about yourself.
Why are they like this? My mother is a narcissist, my father is an enabler, my (younger) brother is the golden child and I was the main scapegoat - when I left home and moved to the other side of the world at 19yo, my sister (youngest child) then became the main scapegoat. My brother attacked her verbally and physically on many occasions but my parents did nothing about it. I only found out years later. I believe my sister's behaviour now is a result of becoming the scapegoat after I left.
I will always feel guilty that I left and didn't protect her (my brother was beyond help by the age of about 12) - although I couldn't have known she would become the scapegoat in my absence, and my brother's behaviour escalated significantly after I left, which I also didn't anticipate/know until years later. So to be fair I don't blame myself but I still wish things could be different IYSWIM.
I'm very envious of people with "normal" (whatever normal is!) loving families - I hope one day to create a loving family unit of my own if/when I have children.