I'm sure all families are different, but there's an expectation that siblings fight a lot until one of them gets too big. Usually it's when the younger one gets big enough to hurt the older one back. (With me and my brother, it stopped when I tried to hit him with a garlic press, missed and hit my hand instead, and cut myself. I was so shocked at my capacity for violence I made sure it never got physical again.)
My kids have never fought. Two girls, 3 years and 8 months apart, you'd think they would have. Number One should have been overly annoyed by Number Two, who was certainly crafty enough to bug her sister deliberately and then play the bullied baby when Number One retaliated. But they never really went there, back when they were 12 and 8, a time I consider prime fighting age.
I started to leave to go to the bank, realized I didn't have my ID, and went back inside. Where Number Two promptly told me the following:
"She was blocking my view of the pantry so I couldn't get a snack, so I slapped her in the face. Very lightly! And she [insert woe-is-me voice here] grabbed my arms and pulled them behind my back and it HURT."
Number One comes out to the kitchen. "Is she telling you about how she slapped me in the face?"
Number One has reached 5'6" and has the nickname "Brick Wall" from soccer. Number Two is about 5'1" but plenty solid and capable of defending herself. They never fought like this before. WHY did they wait until they're 16 and 12 to start the fisticuffs?
Of course, they laughed at me. "We were laughing the whole time, Mom."
Yeah, that makes me feel better.
Note: I sent this to my kids to get their approval before I posted. Number Two said "It's fine. I think it's quite funny." Number One said "yeah, it's fine. i don't know why, but i couldn't stop laughing!"
She doesn't know why?! Guess which kid is my favorite today.