From the moment they are born you know they will love each other and sometimes love to hate each other. It's what siblings do, and for twins it starts even earlier, like in the womb.
There is a 20 minute time limit between birthing one twin and the other. A rule put down in some book somewhere so the body doesn't start thinking it's done (or some crap like that). My boys pushed that limit, and were born 17 minutes apart. I knew soon after that 17 minutes would make a world of difference to the eldest child one day. We chose right then and there to avoid telling them there was an "oldest" child for as long as possible.
It wasn't hard to do, we just never said anything about the time they were born. They were born on the same day and that was it. It was hard enough for them to understand that not everyone has a twin, and that most people aren't born at the same time as their brother.
When they were about 5, they figured out they couldn't have been born at the exact same time. They came to me and asked who was first. And I told them. I was careful to use the word first, without any reference to time.
One of their first grade teacher assistant's happened to be a twin. She approached me a few weeks into school and asked me, "They don't know who the oldest is do they?"
I responded "No they don't"
She said,"You did that on purpose didn't you?"
I just smiled as one of them approached. She understood why I did it and agreed that avoiding one more reason to argue was probably a good idea.
Monday night, while showing off various ways to use body parts to make farting noises, T2 asked me, "Who is the oldest?"
T1 immediately interrupted and said, "I have to be the oldest because I was born first. That's what a girl on the bus said."
(thanks girl on the bus)
T2 said, "Ok he is the oldest, but how much older?"
I was careful in what I would say next, because I knew it would be hard on T2. I asked him if it would matter if he was a day older or a month older like a friend of theirs. He responded that it wouldn't matter, because they are all the same.
"Ok" I said, "T1 is 17 minutes older than you."
You would have thought I gave him a death sentence. He literally keeled over. And then made a farting noise louder than his brother to prove he could still hang with someone older than him.
A little while later, as I was entering their room to tuck them in I overheard this conversation.
T1: You know Mommy says you have to listen to kids who are older than you. (completely out of context)
T2: I AM NOT DOING YOUR HOMEWORK FOR YOU!!!
At least I made it 7 3/4 years before I heard that one.
There are two things in life for which we are never truly prepared: twins. ~Josh Billings