When the US constitution was written a lower age limit of 35 was put in place for the holder of the office of president. This was partly because as the founders looked through history they noticed that the most completely crazy, paranoid and murderous rulers were often those who took office at a very young age.
Roman emperors are a good case in point- most of the really terrible emperors were those who took power at a very young age. For example this list ranks the five worst emperors and I have added their age at ascension in brackets:
- Caligula (25)
- Elagabalus (14)
- Commodus (19)
- Nero (17)
- Domitian (30)
This is not an environment in which openness and responsibility are likely to be nurtured.