The human brain does not fully develop until the mid-twenties, some not until their thirties. The last thing to fully develop is the frontal cortex, which is responsible for reason, judgment, and impulse control. Morality is dependent on all those. Many people look back on things they did in their twenties and cringe, because only someone without a fully functioning brain could have done those things. No one under the age of 25 should be allowed to vote. Sit down, shut up, and listen to your elders... fetus.