Do you have any estranged (not strange lol) family members? How did it happen?

I have a sister who I do not speak to at all. I don't know anything about her, or what's going on in her life currently. I actually haven't spoken to her in about seven years despite us living together for a good 4.5 of those years. I just recently found out she's married. In all honesty, it doesn't bother me, I cannot speak for her though. How did it happen? I honestly don't remember, it's been so long. I stopped speaking to her when I was about 13/14. I was probably over something stupid though.