Having a sibling is like having a forced best friend. They're someone who knows exactly how insane your family is and someone who hangs out with you at family gatherings that your friends can't go to. Siblings are the first non-parent that you interact with during development, and they have a lot to do with how you've turned out. Whether they're older or younger, you have probably learned something from them because you see all of the stupid things they do (and how your parents address those stupid things). The sibling dynamic is pretty universal, and there are plenty of things that we all do with our siblings that we may not do with just anyone.
1. Make faces at each other at the dinner table
Mom said something stupid? Face. Argument? Face. Asparagus? Face.
2. Inside jokes about family members
That family member. We all have one. Or 5. There are the endless jokes about how they are always late to family gatherings, or how they are always getting steak from grandma when no one else is around for dinner.
3. Tease your parents
That one time that they made a fool of themselves on vacation? Y'all will be there to remind them of it at least twice a year.
4. Tease each other
This is pretty self-explanatory. We all have at least an album's worth of embarrassing pictures and videos of our siblings. Watch out, it's like a collection of blackmail for the next time you steal the TV remote.
5. Help each other out
No matter what, you have to get along with your siblings or things are gonna be awkward. There's always a support system with siblings, and there's no one else that knows you better or that you trust more than them.