Growing up as a pony means having your destiny magically determined for you by a life-long image on your butt. Whatever that image comes to be, whether it's a thumb tack or an inexplicable desert island, will be the one thing you're truly good at above all else. For this reason it's both a rite of adulthood and a kind of hazing ritual to gain and celebrate the cutie mark. Most children are afflicted at a very young age, but continue going to school anyway in spite of being imbued with all knowledge related to their craft by sorcery.