"Kings inherited their positions regardless of their ability to rule the country." Yes, but the son of a king was also trained from birth for the role of being

"Kings inherited their positions regardless of their ability to rule the country." Yes, but the son of a king was also trained from birth for the role of being a regent, something few if anyone else could have said. This didn't make him the best for the job but it did allow a period of on-the-job training and a cadre of ministers and assistants who DID get to their positions by merit to guide the crown prince. Setting aside the specific role of monarch, it was typical for sons to take up the same job as their father for similar reasons: they were exposed to knowledge about the trade and mentored in it from a young age. I don't know what happened to children who showed no aptitude/merit for following in the parent's profession -- I suppose it depended on the wealth of the family or the child's ability to find a patron to pursue some other career. But I wouldn't immediately dismiss former times when one typically took up the career path of their parent as being without merit.