Children are ignorant. Stupidity is learned.
Because it’s hard for me to resist lexicology discussions… 
Yeah - I agree that ignorant might be a better word choice than stupid. To me, stupid seems kind of like a more permanent or semi-permanent condition. Assuming stupid basically means unintelligent. Whereas a child’s lack of experience and undeveloped brain are temporary conditions.
Although I have to disagree on learning stupidity. I don’t think you can learn how to be stupid. I think it’s kind of the opposite, really. I think of stupidity as the inability to learn. I.e. unintelligent. But that’s just my take. YMMV.
