It's quite interesting that GD Konstantin K. from time to time said to his wife that Ioann was like him and was the most similar to him in nature. The most common opinion is/was that Prince Oleg, the most talented son, was like GD KR, but KR itself admitted to some courtier Oleg was only similar to him in his poetic experiences but Ioann had the same as father's uneasy and turbulent character.