Personal Science
There are a lot of other things we figure out during that time of life, as well. Basically, we are learning the rules of this new game we've been thrust into, called Life. Once certain lessons are learned, they can be internalized and you can stop testing them. Like gravity. It's pretty reliable for babies on earth. We take it for granted. In fact, if it isn’t learned and internalized, chances are that juvenile human will die.
How do you want to be defined? By one action? By some opinion that could evolve? By a mistake, regrettable only with hindsight? Or by the sum of your parts? Okay, do that for other people. Start the trend.