Well, having read some of these, I suppose it would be my own younger sister. In the 1990s, as our father was dying, our mother already passed away. One night at her home she told me about some family history of which I was unaware.
Turns out she had become pregnant out of wedlock when 17, of which I knew nothing, shortly after I had entered the Army in 1969. Our parents refused to let her get an abortion, and when the baby was born, our mother insisted she give it up for adoption, which my sister didn't want. But at not quite 18, my sister had no legal standing, our parents in control.
And the argument our mother used with her was that her older brother (me) would never approve of her keeping the baby! Well, yes I would have! But I was never told nor consulted, just our mother's excuse for her own decision. I should note, as I've posted on RJ before, that beginning at age 13 I was placed in charge of our family's affairs by our parents.
An odd thing, I know, but this is what they did, that I've explained in detail here. And so our mother claiming her decision was due to me was not inconceivable to my sister. I was, in some respects, the "head of the household" from age 13. Yeah, think about it. Perhaps our parents were also nutcases.
So my sister lost her baby to enforced adoption, and always resented me personally for it, though I had no knowledge of it. But wait, there's more...
Years later, my own second son was born. And his mother & I decided to name him after his late uncle, his mother's brother. As I am named after my own mother's late brother, killed in France during WWII. And it made her mother, our son's grandmother, very happy that a family name would live on.
Except... unknown to me, it was the SAME NAME my sister had put on the birth certificate of her own bastard son years earlier. What a weird & incredible coincidence! So that when, years later, we named OUR son that, she and my parents assumed I had learned about my sister's bastard son, and given our own son the same to upset her! Like I would give my son a name solely to insult someone else! What craziness!
So I explained all this to my sister, my total ignorance of what had transpired, my opposition to what our mother had forced her to do, and you know what? She said she still blamed me for losing her son! I would be forever guilty for her losing her son that she wanted to keep. Plus she told me she hated me for being gay, which she also told me our parents had always known, from my childhood, and talked to her about, but never they said a word to me about it.
I haven't spoken or communicated with my sister for 14 years. Nor will I ever. After that, I was done with her. I don't need a sister like that.