Who knows? I have two sisters, both older than I am. The younger of the two frequently gets royally pissed at the other and cuts off communication for some variable period of time. Somehow I escape that, even though I’m just as likely to say something she won’t like.
Maybe it’s because it’s her older sister, the one who sometimes got to be the fill-in Mom briefly. Or maybe the older one’s advanced snarkery skills are the cause.
I just ride with it, talking to one on Tuesdays and the other on Wednesdays.