Pony Ages · 4:38am Mar 3rd, 2014
I've realized several of my stories have made assumptions about the maturity level of the ponies, so I shall attempt to explain my logic here.
Based on Digibrony, the Mane Six are around 15 years old.
I believe ponies consider a 15 year old pony a full fledged adult. Based on Twilight, she finished as much schooling she could manage and "graduated" when she ascended to Princesshood, putting her at what we might think of as 26 years old. In the first season, Rarity seemed intent on courting Blueblood for the purposes of marrying him, which also aligns well with that age.
But even so, they still have only had 15 years of experience with life. Thus, they would still be finding truths about the world around them, thus making their letters to Celestia be perfectly reasonable for their age.
My adult-themed stories are generally depend on their adult role in society being about 26 years of age, but with the mind of a 15 year old.
