I am an only child. As such, I often hear the question “Don’t you wish you had a sibling?” (or some similar variation). When I was younger, I leaned toward “No”, but wasn’t sure. The older I’ve gotten, the more firmly I feel about the answer. Now, the answer is “A 100% hard NO”.
Perhaps I wouldn’t feel so strongly if it wasn’t for the fact that many times I’ve been asked about wanting siblings immediately after the asker has just finished telling me some horror story about something awful their sibling(s) did to them. For example, “Yeah, my brother cut off all my hair and decapitated all my dolls. He’s such a dick. I love him though. Don’t you wish you had a sibling?” And then the asker is all surprised and shocked by the fact that I don’t lament not having grown up with someone who constantly harassed me and destroyed my stuff.
I was reminded of this recently because I am reading the “Nihongi”. The first section has a few variants of the myth about Amaterasu, the sun goddess, running away and hiding in a cave. What caused her to do this, to plunge the world into darkness? Her brother, who was being a huge asshole to her. Seriously, he was a HUGE asshole. He wrecked her heavenly rice crop, which is bad enough. He also killed a horse and THREW THE CORPSE AT HER. Then, because he clearly wanted the title of God of the Pricks, he went into her home and just took a shit (in one variant, it was under the chair she always sat in).
In conclusion, do I want a sibling? HELL FUCKING NO. And mythology backs me up on this.