Did you also think that perhaps he may just be a really smart guy with a love for math? You have hobbies, don't you? Reading, playing video games, insulting people out of ignorance, you get what I mean. Well what if there was a kid, who's hobby was math? It's a ridiculous idea, I know. Possibly so ridiculous that I could be lying to you, or you could just be really close minded and amazingly ignorant.
In any event, there are plenty more cases of 12-year olds who are studying in uni to become Marine Biologists and Heart Surgeons. I don't see why the concept is so hard to grasp. Not to mention this is a really weird thing for anyone to lie about, and you officially go under my book of reta.... 'weirdos' for accussing him of lying and being offended for a lie that he has never told...