DarkLaw316

It could be possible since a cutie mark is somewhat based around a pony’s destiny for example in magical mystery cure each one of the mane 6 started following what their mark was telling them. If an adult pony doesn’t have a cutie mark there are some possibilities such as their cursed,they reject their calling in life/destiny , they could still be trying to find there calling in life, or as many say an animation error.