Its very exciting when this happens.
Dd was the same. Fantastic vocabulary, could count at 18 months, could read and write before reception. And she is the youngest in her year.
At four she was explaining how a nuclear reactor works to her engineer uncle. She is actually following in his footsteps.
Dd is now 13 and does well at school. But not gifted or talented and maths isnt her strongest subject. She has to work hard to be good at it.
Ds was the opposite. Late talker, not interested in reading or writing or counting.
Ds is 6 and great at maths. Far above his peers at the moment. His reading and writing is excellent too. I can imagine that at 13 he will be around tge same place as dd. Doing well but not freakishly so.
Some kids just develop differently and at different times.
My mum wanted dd enrolled in a programme for gifted children as an extra curricula. Me and dh didnt. We wanted her to go at her own pace.
Also i have no idea where the kids brains came from. Me and dh arent massivly intelligent and just did ok at school. Although we both probably have done a lot more studying since we hit 25.