My child said that his Dad knows everything because he is tall and I don't because I am short...by the way I am not short!
I am answering him that IQ is not equivalent to people's size, but he does not matter to him!
pia
You might want to show him some photos of famous smart people that are "short" and show him that "short" people are just as smart and that he is "short" but he still very smart.