I had a hard time estimating, although thinking back I know I was probably in denial. DS was incredibly advanced, reciting "The Jungle Book" dialogue by typing it all on the computer with near to perfect spelling/punctuation at age 3.10. I just didn't know if he were just a high achiever with a somewhat high IQ or actually way out there IQ wise. I can't say I was surprised when I found out he was well into the PG range.