YoungerCub, being only 3, hasn't got the concept of being anything, as far as I can tell. He's quite looking forward to being a 'full-timer' at school though.
Big'un did want to 'mend computers like mummy and daddy'. Then he wanted to be a teacher, like his (male) reception teacher. Then he wanted to be a builder, so he could build a bigger house. Currently he wants to either be a scientist or an inventor.