MUST democracy be maximally inclusive ??

Question

i.e 1) what about 16 year olds who are competent to make decisions and must abide by laws...but are excluded from participating.
2) Also, the insane and criminals are excluded from voting, thus this seems to make inclusion contingent on qualifying to participate, is this democratic?
3) In Athens, 'citizens' were allowed participatre...but citizens were only one fifth of the population! I I argue against the question asked. Do you agree?

Answer 1

Democracy must allow that the age of majority be lowered to 16 years old. Criminals and Insane persons can vote during lucid interval. Citizens must be allowed to participate in determining government policies.