DD9's cardiologist first noticed when DD was 6 days old - she was having a cardiac ultrasound (her heart is fine, btw

) and she tried to push the ultrasound wand off her chest twice. DH and I were too worried about her heart to notice but the cardiologist was impressed: "they're not supposed to be able to do that at this age."
Fast forward through months of precocious interest in books and comprehended vocabulary to about 11/12 months or so when she could draw faces, and a friend of mine said "you should have her tested."
Then when DD was 16 months I consulted the baby/toddler books to see when kids typically master the alphabet and realized how far ahead she was. That sealed the deal for me, and advanced became the "new normal."
Poor DS came along and mastered the alphabet at 24 months, so I thought he was delayed, lol. Chess at 6 (which I though nothing of - he made it seem so easy - I was stunned when none of his classmates could handle it) and precocious math ability made me think he might have some extra gas in his tank as well.
I'm quite certain neither one are at DYS level... my guess is MG/HG maybe (I'm HG, so there may be a genetic similarity). With DS it's so hard to tell because he has diagnoses (ADHD & language processing deficits) that roadblock him.
A friend of mine had no idea her son was HG until he was tested in grade two - the school thought he had Asperger's (he doesn't). This mom was quite shocked

Isn't it funny how they can all present differently

On a related note: we have an upcoming scheduling conflict between DD9's pull out math gifted program and a class field trip to the airport. She chose math

"If I want to know how the airport works I can just google it."