The same thing happened to me ... Great father then bad son specially in influance . So , I tried some ways to get him better :
1. by war : use your son as the great commander of your armies .
2. try to bulid bulidings that don't spend a lot fo time and put all the generals that carry their titles in the army of your son so he will get Magnifitic bulider very fast .
3. try to bulid relegion bulidings so gain peuos .
all of these vices let people think that heir when role will be the greatest so I think he will gain more influance .