I'm looking at turn 124 of a game with standard Procipinee as my sovereign. She took a champion to wed fairly early and has three offspring, but the UI describes her as just 24 while her firstborn is already 15. I'm pretty sure she was '21' when the first kid arrived. Not a big deal, but definitely odd for anyone who looks at and thinks about numbers in the UI.
Unless the sov age has game value, it doesn't really seem necessary to display. And unless a numerical age for offspring is significant, it doesn't really seem necessary either and could easily be replaced by terms like infant, child, marriageable youth, marriageable adult...