Why are child genuis only revealed to the world once they are older? Why are their earlier extraodinary developments never really recorded eg child started talking age 4months etc?

Surely a 6 month old baby saying to a doctor that he has a middle ear infection would make the news or something or be recorded somewhere before the baby even reaches university at the age of 8 etc. The baby example is given on this website http://www.oddee.com/item_96629.aspx it always strikes me as interesting that there is no record of ‘proof’ of children speaking this clearly this early it is always what is said later on. If a baby is speaking this clearly surely it is a genius for that in that moment not only because they later go on to do a uni degree before most kids are even out of primary school.

It just kind of bugged me when I read that about the baby telling the doctor that because I wonder if it is true. Do you think it is possible a 6 month old could actually really say that – even a genius one?