Nor does a lifetime of benefit scrounging, nor indeed a lifetime of prestigious employment.
Intelligence is mostly down to genetics, dumb remains dumb, nothing will change that.
Ignorance on the other hand is down to education and these days there is little excuse for ignorance, the facts to inform oneself of at least the basics of any political argument are readily available to practically everyone in a developed country such as Britain.
It is the thick and ignorant that I would rather not see at polling stations regardless of age, if a 16 year old has enough interest to turn up at one then chances are they are likely to have informed themselves at least a little bit.