Lol same!
Exactly. Plus, all of the family friends that become uncle this or auntie that.I don't think family dynamics and who calls who what is set in stone for everyone. I've had a case where someone younger than me is sometimes called "big" simply because of how much they take care of everyone around them as if they were indeed a big brother.
I'm even to the point where because I grew up very closely with three of my cousins, we introduce each other as brothers on reflex.