Ostracism. When we were kids my cousin lived with my grandparents and she'd turn my sister and I against each other, either she and I against my sister or, more often, her and my sister against me.
When I was ten my grandparents stopped speaking to us, told us not to come for Thanksgiving and Christmas. I don't know why. My father wasn't welcome in their home. After Thanksgiving I wrote a letter to my grandmother inviting her to Christmas at our house. That broke the ice and she called my mother and we all had Christmas together.
When I was 30 I moved in with my mother and came face to face with my grandparents, my two aunts, and one cousin's habit of excluding my mother, and now me, from family get togethers. It's not like we had some huge family, it's really just a few of us, but they had done it before, and here I was living there now and my cousin's birthday came up and nothing. I left a present on her doorstep and a week later I found out they'd all gone out for dinner. We're not poor, obnoxious, violent, or anything that would easily explain or excuse it.
After my mother went to confront them the entire family stopped speaking to us for several years. My grandmother died two years later never having spoken to me again. My grandfather died in 2013 never having spoken to me again. I haven't spoken to my cousin. My aunt emailed me after eleven years of silence hoping she could come to my mom's for Christmas, a year ago. I saw her again at my father's funeral. She didn't come for any holidays this last year.
During the 90's my father stopped speaking to me for five years after cutting me off. Then around 2007 he decided told me that because of my emails, which were infrequent, but rambling and confusing for him, he was in danger of taking up drinking again, and so he wouldn't be contacting me again and didn't want me contacting him and wasn't interested in any kind of relationship, which he said we didn't have anyway.
Almost exactly a year later he called to say he'd changed his mind.
I'm glad the ones who are dead are dead and I hope the others will soon follow. In a fire.