snortles. this is actually a funny one. partly makes sense to me. she is not even an adult filly even in series. besides, their apple orchard isn't own by any singular family member to begin with.
though that is a big question i think. we know about rarity's family, twilight sparkle, whom to this day i think parodies a certain stupidity made novel, and even pinkie pie, as we know her family is still working on their rock farm. we still do not know the status of rainbow dash, fluttershy, and of course applejack here.
There's also a theory that the shooting stars in the Apple Reunion episode were AJ's parents. Literally. Her parents are wonderbolts who spend so much time away from their family, that other ponies mistake their children as orphans.