Gullibility

Linus: You don't believe the story of the Great Pumpkin? I thought little girls always believed everything that was told to them. I thought little girls were innocent and trusting.
Sally: Welcome to the 20th century.
--It the Great Pumpkin Charlie Brown

Kids are gullible because they have not yet developed their capacities for reason and critical thought that they were endowed with. Adults are gullible because they do not use their capacities for reason and critical thought that they were endowed with.

Those who seek power know this and seek to exploit it.