It be nice to think that an able child would be able to reach their potential with parental support to fill in the gaps. I just don't believe that this is always the case.
My DD wants to be a vet, she has done since yr 3. This may change but we have to look at how a school would support her current aspiration. Our state catchment school is a 'sport specialist school' (I think on the basis that it is rubbish at anything academic so sport is the best they can focus on)
which got a score of 4 across the board at the last inspection and it only offers double science. I would struggle to teach her the third science to any degree, let alone to A grade standard. There is no way she would get the kind of grades there that she would need for vet school.