I'm going to be honest with you here. I've struggled with this question today. I've struggled just putting pen to paper today, but that's a whole different ball of wax.
The simple answer to the question, "When did you realize you were a grown up?" is that, I haven't.
Sure, I've had those "defining moments" - graduation from university, death of a parent, buying a house all my own, getting married, being a wife, but through all of those things, well, I've felt like a fraud. There, I said it. I often feel like a big fat fake; like someday, someone is going to figure out that I've been skating below the radar and I shouldn't be considered a grown up anymore. Often, I find myself in disbelief when I do something an "adult" would do. It's almost as though my sub-conscious knows I've just been faking it for the last fourteen years.
My mother, rest her soul, always proclaimed that she never grew up. She was proud of the fact that people thought she was younger than she was. She loved being silly and goofy (and oh how my teenage self loved that). She loved dancing around without music. She adored puppets and marionettes - especially making the weird voices. She liked to make my stuffed animals talk. Yeah, it was weird - but the underlying truth was that, the best part about being a grown up - is that you don't have to grow up.
When I was a teacher I saw kids strive for adulthood; some already knowing way too much about the world around them. They loved the thought of having money and freedom and a car. They, like me at their age, didn't understand that the biggest freedom in being an adult is that you can act like a kid and that's OK.
So my mom rubbed off on me. I love playing with Legos, swinging on a swing set, watching the Muppets and Fraggle Rock and dancing my way (much to my husband's embarrassment which is kind of a bonus ;) ) through Target.
Just like her, I hope I never grow up. She was right, age is just a number, being an adult is just a mindset you craft yourself and you might have to grow old, but you never have to grow up. Thanks mom.