I don't think so... so far, the Heir position is a blank slate. They could have fighting skills or not at all. They could be charismatic or shy. Noble or spoiled. They would have gotten a good education and morals out of their uncle, so the most likely thing is that they won't be a wild child or ignorant but that's about it. If the heir has points he or she is found lacking in, then he or she will have to depend on the other players, his aides, companions, friends and allies to make up for it. The rest of the requirements are same as above, just that they must be 18 years old and raised by his uncle. 

Oh, another important point is that they have been kept away from official life as much as possible during their upbringing. Takeshi has a manor on a village away from the capital of the Mitsumine territory and from there is where he has ruled while raising the Heir. While the heir has not necessarily been kept in isolation, they have purposely been kept apart from court life, manipulators and the big city while Takeshi tries to educate them. Private visitors, family members and friends as well as the people of Takeshi's village would not have been kept away, so the Heir has had access to plenty of social interaction should their player be inclined to it.